The doctrine of the eternal generation of the Son (EGS) has fallen on tough times in evangelical and Reformed circles. Though an indispensable component of classical Christian theism as confessed in the Nicene Creed, much of modern scholarship has dispensed with it in favor of other Trinitarian theories.
But rejection of EGS can have significant consequences for the church’s understanding of Christology. Traditionally, the doctrine of EGS sought to convey and safeguard at least two major truths: (1) the Son’s full consubstantiality with the Father (homoousios), and (2) the Son’s distinct personhood (hypostasis). EGS explains how the Son is both essentially equal with and hypostatically distinct from the Father. It does this because it asserts the eternal communication of the entire, undivided divine essence from the Father to the Son while providing the ontological basis for the distinction of subsistence due to its distinguishment of the individual, incommunicable properties of unbegottenness relative to the Father and begottenness relative to the Son. Denying the doctrine of EGS divests the doctrine of the Trinity from the metaphysical basis of asserting full equality of substance and distinction of hypostasis between the Persons of the Godhead.
A thorough defense of the doctrine of EGS would seek to provide a satisfactory answer to the numerous challenges that have arisen. While that is needful and is being done, I think a more effective method—generally speaking—for persuading the conscience of the typical evangelical or Reformed believer is to engage in direct interaction with the biblical text. One of the reasons for the declension of believing in EGS in our day is because it has often not been demonstrated biblically in a manner that would satisfy the sincere doubts of its inquirers. Some important thinkers have denied the doctrine because of linguistic reconstructions of the term μονογενής that deny that begottenness pertains to its meaning, as if the entire doctrine of EGS rested on a single Greek word. But the Fathers who formulated the doctrine did not depend merely on a single Greek word. They used an array of biblical texts and arguments to substantiate it.
One of the most neglected texts they often cited in defense of the doctrine of EGS is Hebrews 1:3. It was such a foundational text to them that the phrase “light of light,” ascribed to God the Son in the Nicene Creed, was extrapolated from their understanding of this text. In spite of its weighty credal precedent, the import of this text for EGS has received relatively little attention in modern scholarship. We shall engage in exegetical and theological reflection on the first clause of Hebrews 1:3 in defense of the doctrine of EGS. Our contention is that this passage bears testimony to the doctrine of EGS and that the doctrine cannot be disregarded without doing violence to the clear biblical testimony which describes the Son as “the brightness of [God the Father’s] glory, and express image of his person.”
Ontology or Economy?
The first question that needs to be resolved as we approach the description of the Son in this text is to what aspect of the Son’s being or state it is referring. Three major options lie before us: the Son is the brightness of the Father’s glory and express image of his Person (1) ontologically in his eternal divine Person; (2) economically in his mode of mission as Mediator incarnate in human flesh and revealed to the world; (3) in his Person as considered from the perspective of the writer to the Hebrews, which could include his divine Sonship and incarnate mediatorial work or specifically have in view either one or the other.
The hermeneutical distinction as to which “form” of the Son a particular description of the text may be predicated has long been employed by the orthodox in formulating Christology based on exegetical reflection. Augustine aptly summarizes this approach in his On the Trinity when he points out that Philippians 2:6–7 describes the Son as existing in the “form of God” and as “the form of a servant.” This distinction articulates a hermeneutical “rule” (as Augustine calls it) that can be applied to the specific Christological predications of Scripture. When Jesus says, for instance, “I and the Father are one” (John 10:30), he is predicating that statement of his divine Person as “the form of God.” But when he says, “The Father is greater than I” (John 14:28), he speaks in “the form of a servant.” It is important not to take a predication that is biblically intended to describe one “form” and ascribe it to the other form, or else one may misinterpret the text, and potentially end up with serious Christological and Trinitarian error.
In light of this rule, should we understand the description of the Son in Hebrews 1:3 as “the brightness of his glory and express image of his person” as a predication of the Son’s divine ontology or of his mediatorial economy? If it is the latter, then it would probably have little to do with the doctrine of EGS (at least directly), since EGS belongs properly to the Son’s μορφῇ as God. But if it is a description of his divine ontology within the Godhead, then it could have vast implications for EGS, since it would be giving us statements that pertain directly to the Son’s eternal relationship with the Father within the immanent Trinity.
In favor of an economic position are arguments that point to surrounding contextual indicators in Hebrews 1 that would indicate that the Son’s economy of redemption is what is primarily in view. In verses 1–2, redemptive history is summarized and appears to be the primary concept of the pericope. Moreover, in the latter part of verse 3, the Son’s purging of our sins and his sitting down at the Father’s right hand apply particularly to his economy. His humiliation and exaltation are definitely predicated of the Son in “the form of a servant” and not properly of him “in the form of God.” Since economic predications sandwich the Christological assertions at the beginning of verse three, would this not indicate that mere economy is in view?
Not necessarily, because there are other indicators that ontology is also in view. First of all, verse 2 calls the Son “the Son,” which he is eternally in relation to the Father. That is ontology, and it immediately precedes the following descriptors of verse 3. Second, the purpose of the passage is to declare the supremacy and pre-eminence of Christ above all, as John Owen points out, “not only consequentially to his discharge of the office of mediator, but also antecedently, in his worth, fitness, ability, and suitableness to undertake and discharge it,—which in a great measure depended on and flowed from his divine nature.” In other words, the author grounds Christ’s all-sufficient work in his matchless divine Person, which is the foundational truth of the epistle’s entire paraenesis. Third, and confirming this, verse 8 explicitly calls the Son ὁ Θεός in citing Psalm 45:6, while verse 7 commands all the angels to worship him. Much attention is given to his divine ontology as the eternal Son.
This means that both economy and ontology are in view in verses 1–3. The divine Son has become incarnate to accomplish redemption. Rather than either/or, there can be an interspersion or even overlap of both, leading to a more nuanced position that better explains the Christological predications of the passage according to authorial intent. Owen is right when he says:
“It is not the direct and immediate design of the apostle to treat absolutely of either nature of Christ, his divine or human, but only of his person. Hence, though the things which he mentioneth and expresseth may some of them belong unto, or be the properties of his divine nature, some of his human, yet none of them are spoken of as such, but are all considered as belonging unto his person.”
Building on this, a number of the Christological assertions of vv.1–3 cannot be limited to either/or for they encompass both concepts. Verse 2 says the Son was “appointed [ἔθηκε] heir of all things.” This appointment has its ground in the intra-Trinitarian pactum salutis (cf. Pss. 2:8; 110; John 17:6, 11, 24; Titus 1:2), which is an eternal decree, and thus involves the Son in his preexistence and eternity (John 17:5), corresponding to his divine nature. But while it necessarily presupposes the ontology of a preincarnate Christology, it also encompasses the economy of redemption, for this appointment as heir did not reach the historic inception of its telos until the incarnate Son’s exaltation (Heb. 1:4). Thus, the statement forms a bridge between ontology and economy. So do the following assertions that ascribe to the Son the work of creation (v.2) and providence (v.3). Only God, as God, creates and upholds the universe. But again, these are economic works of the Trinity ad extra. The statements incorporate both concepts, building on ontology and extending to encompass economy. And all that Christ did in the “form of a servant” encompasses economy.
If we apply this dynamic specifically to the assertion in verse 3 that the Son is “the brightness of [the Father’s] glory,” could we gain some insight into EGS and its relationship to the Son’s mission in redemptive history? I think we can. Is it justifiable to apply this dynamic to this assertion? I think it is, as I hope to demonstrate. Hebrews 1:3 does have bearing on the Son’s generation and relationship to the Father even as it grounds his manifestative mission in the world (cf. John 1:14) in his intimate ontological Sonship πρὸς τὸν Θεόν (cf. John 1:1).
The Brightness of the Father’s Glory
The Son is “the brightness of the glory” (ἀπαύγασμα τῆς δόξης) of God (Θεὸς, which is the antecedent [v.1]). To get at the meaning, we must inquire as to (1) what is meant by “God,” with whom the Son stands related; (2) what is signified by “the brightness of the glory” of him; and (3) how this relates to EGS.
First of all, what is meant by “God” (v.1)? God spoke in the past by the prophets, but in these last days he has spoken to us ἐν υἱῷ. The distinction between “God” and the “Son” indicates that the Father is the one particularly signified. This is in keeping with standard New Testament (NT) usage, which typically refers to the Person of the Father by the generic title, “God” (Rom. 15:6; 2 Cor. 1:3; Eph. 1:3; Col. 1:3; 1 Pet. 1:3). This indicates that sometimes, even often, Θεὸς may be used with distinctive paternal connotation and emphasis. That the text says Θεὸς and does not specifically say πατήρ should not be taken to indicate that the title Θεὸς is not intended to refer to the first Person of the Godhead with a particular view to his unbegotten Fatherhood. Θεὸς might not be familial language per se, but its semantic meaning in the NT when used vis-à-vis υἱός necessarily involves familial/paternal/filial overtones that need not be explicitly declared by the title “God” for such familial concepts to be inherently present in a given occurrence of the term. The Son stands eternally and ontologically related, not just to ‘God-ness’ or deity generically, but to the Person of the Father particularly, as “the brightness of his glory.” The text speaks of God the Father in his particular subsistence as Father.
Second, what is signified by ὃς ὢν ἀπαύγασμα τῆς δόξης? The description applies to the Son ontologically as “the form of God.” The “brightness” specifically described here is not of the common divine essence (οὐσία) shared by all three Persons of the Trinity, because the juxtaposition of this description of the Son relative to the Father suggests that this description belongs properly to the Son and not to the Father as such. The Son shares the Father’s δόξα because the Son is the ἀπαύγασμα of the Father’s glory (the radiance is unique to the Son while the radiance proceeds from its fontal glory and effectively effulges that glory because it partakes of that glory). ἀπαύγασμα is a description of the subsistence, the hypostasis, of the Son in his personhood in relation to the Father. So, “glory” is common to both and “brightness” is unique to the Son. There is full equality of glory while there is distinction of Person. There is also relationship of derivation. “Glory” and “brightness” are of the same nature, but the brightness derives from the glory. It is from this exegetically deduced theological reflection that the church fathers sagaciously creedalized that Christological description, “light of light” (φῶς ἐκ φωτός).
Applying the analogy of Scripture to these insights helps us to expand and clarify them. God’s glory is described in Scripture as consuming fire and radiant luminosity (Exod. 3:4; 24:17; Ezek. 1:27). “God is light” (1 John 1:5; cf. Hab. 3:4). The Father dwells in inapproachable light (1 Tim. 6:16). But the Son shines with the light of his glory (2 Cor. 4:4–6). The Son’s countenance is like the sun shining in its strength (Rev. 1:16). Describing the New Jerusalem, the apostle writes, “And the city had no need of the sun, neither of the moon, to shine in it: for the glory of God did lighten it, and the Lamb is the light thereof” (Rev. 21:23). The Lamb is the illuminating radiance of the glory of God. “The Sun of righteousness” (Mal. 4:2) is the brightness of the Father’s glory, so much so that he will illuminate the entire new creation. This radiant shining with God’s glory is predicated of the Son because of who the Son is in relation to the Father.
In these passages, there is an analogy conceptualized. Commenting on Hebrews 1:3, John Owen admits, “the apostle intends to set forth unto us the relation of the Son to the Father by an allusion unto the sun and its beams.”This was one of Athanasius’s preferred analogies in defending Christ’s divinity against the Arians. Removing from the analogy any creaturely imperfection or finitude, it illustrates the Son’s consubstantiality and coeternity with the Father. In the words of the Alexandrian Bishop: “Who does not see, that the brightness cannot be separated from the light, but that it is by nature proper to it, and co-existent with it, and is not produced after it?” Owen summarizes the significance of the phrase in one terse sentence: “That he is one distinct from God the Father, related unto him, and partaker of his glory, is clearly asserted in these words.”
Third, this illustration of light generating a consubstantial radiance, understood in conjunction with the exegetical deductions summarized under the two points above, informs the doctrine of EGS. Corresponding to Owen’s conclusion, we can say: the Son is “related unto him,” that is, he is generated from the Father so as to be the eternal Son in relation to the eternal Father. He is eternally begotten of the nature (οὐσία) of the Father like radiance is generated from the source of light and partakes of it. The analogical correspondence between light with the procession of radiance and the Father with the procession of the generated Son is unmistakable if ontology is in view in Hebrews 1:3. The Son is also “one distinct from God the Father” in that he is not the same hypostasis, in an analogous manner to the way that radiance is distinct from its light source, like the rays from the sun. Furthermore, the Son is “partaker of his glory,” says Owen. Being generated of the Father, of and within his essence, he possesses the full divine glory. The sameness of nature between the radiance and the light signifies consubstantial equality. Scott Swain summarizes it well when he says,
“The imagery of Hebrews 1:3 suggests that the Father should be understood as the natural principle of the Son—as light naturally radiates its brightness, so too God naturally radiates his Son… the First Person of the Trinity is, properly speaking, fatherly principle to the Second Person of the Trinity.”
Hebrews 1:3 intimates eternal generation, and it upholds the twofold truth that the doctrine of EGS implies: equality and distinction.
Summary and Conclusion
That the Son is “the brightness of [the Father’s] glory” is predicated, according to the authorial intent of the Hebrews epistle, of the Person of Christ. As such, the description pertains properly to his divine nature as “the form of God” and discloses something of his filial relationship with the Father, which enables this statement to provide exegetical insight into the doctrine of EGS. Likening the Father-Son relationship to the sun and its rays, or to a light source with its beams (as supported by the analogy of Scripture), while excluding from the analogy any creaturely attribute improper to God (as Scripture also teaches), the phrase is meant to convey the Son’s oneness with the Father in nature, distinctness from the Father in Person, and equality with the Father in glory.
This glorious reality of divine Sonship as the ontological expression of the Father’s glory is redemptively manifested in the auto-revelatory act of the Son’s economic mission which constitutes the climax of redemptive history. The Son’s economic mission beginning with his becoming “in the form of a servant” is the accommodated, redemptive manifestation of the divine ontology. All this helps to explain why the doctrine of EGS is not a fruitless inquiry into mere speculative theology. It is not inconsequential whether we affirm it or not. It cannot be denied, as is being done by many a modern theologian, without causing significant repercussions to the church’s understanding of the structure of the Trinity’s redemptive mission.
Another way to say this is that EGS is central to the logic and theology of the gospel, just as the orthodox church fathers taught. As the Son is consubstantially the radiant light of God’s glory and the ontological image of the Father in eternity by virtue of his eternally generated Sonship, he comes to the world on mission to reveal that reality in an accommodated mode of redemptive self-disclosure. His ontological divine Sonship is indeed the archetypal reality that provides the pattern for his mediatorial human sonship. His eternal generation is the archetypal reality that made it fitting for him as the perfect Son of God to become the perfect Son of Man, incarnate for our salvation. Clothed in human flesh, the Person of the Son radiates with the light of God’s glory and images the Father to the world so that we may behold the invisible image of the Father in the visible face of the Son who perfectly resembles him (2 Cor. 4:4). As he always was intimate with the Father in eternity, the Son comes to embrace us into union with himself—to make us “sons in the Son” —so that we, through him, may dwell in God, and God in us.
The Son’s eternal generation is the ground of his perfect ability to “save to the uttermost those who come to God through him” (Heb. 7:25). His matchless Person as eternal Son, “light of light, very God of very God; begotten, not made” grounds his finished and all-sufficient work as the perfect and consummate Author of redemption and Revelator of God. That is what the Nicene Creed is about. But more importantly, that is what the book of Hebrews is about, and that is what the gospel is about.
 There are a number of reasons for recent denials of EGS. For one, doing theology in an independently biblicistic and somewhat autonomous manner has resulted in theologizing on Christology apart from engaging in careful conversation and sober reflection on what the luminaries of the church have taught in past centuries. This results in not only ignorance to their teachings, but failure to consider and be persuaded by their arguments. Second, modern culture is evincing a distaste—even disdain—for the creeds and confessions of the catholic Christianity of the past. Such documents and their formulations are increasingly viewed as antiquated relics of a pre-critical era, easily dispensed with in favor of alleged new discoveries. Third, the doctrine of EGS in its profundity is rife with metaphysical concepts that utilize philosophical categories in reflection on the biblical data, and many strands of modern theology are skeptical of any rational thought that would theologize by employing categories derived from philosophy, not to mention the metaphysics derived from a Christian/Augustinian Platonism or Aristotelian scholasticism. Fourth, critical exegesis in this post-Enlightenment era engages in a hermeneutical method that differs in important ways from pre-critical exegesis; though it deals with the same biblical texts, it does not yield the same theological conclusions from those texts. The failure of modern hermeneutics to arrive at the doctrine of EGS is consequential of its rejection of employing an informed Trinitarian metaphysic in assessment of the exegetical data of a given pericope of Scripture while simultaneously refusing to employ a canonical (i.e. whole Bible) approach to the interpretation of individual passages of Scripture. Each of these tendencies in modern scholarship poses a threat to the doctrine of EGS. And each one is, notwithstanding, plagued by internal inconsistences, philosophical incongruence, and hermeneutical problems. For a more thorough defense of EGS, see Fred Sanders and Scott R. Swain, eds. Retrieving Eternal Generation (Grand Rapids: Zondervan: 2017); Kevin Giles, The Eternal Generation of the Son: Maintaining Orthodoxy in Trinitarian Theology (Downers Grove, IL: IVP Academic, 2012); Francis Turretin, Institutes of Elenctic Theology, ed. James T. Dennison Jr., trans. George Musgrave Giger, vol. 1 (Phillipsburg, NJ: P&R Publishing, 1992–1997), 292–302 [Institutes, 3.23.8; subsequent citations will follow this abbreviated format].
 An example of this can be seen in Appendix 6 in Wayne A. Grudem, Systematic Theology: An Introduction to Biblical Doctrine (Grand Rapids: Zondervan, 2004), 1233–1234. For a linguistic defense of μονογενής ordinarily conveying begottenness, see Charles Lee Irons, “A Lexical Defense of the Johannine ‘Only Begotten’” in Retrieving Eternal Generation, 98–116.
 For an overview, see Giles, The Eternal Generation of the Son, 91–171.
 It is perplexing why many denials of the doctrine based on an alleged lack of biblical support for it do not even mention Hebrews 1:3. E.g., John S. Feinberg, No One Like Him: The Doctrine of God, The Foundations of Evangelical Theology (Wheaton, IL: Crossway Books, 2001), 488–492.
 Hebrews 1:3 factors prominently into the early Christological debates surrounding Christ’s personhood and deity. The Fathers would often cite it as a proof text against the Arians to prove that Christ is ὁμοούσιος τῷ πατρί. See Francis M. Young, “Christological Ideas in the Greek Commentaries on the Epistle to the Hebrews,” in Christology, Hermeneutics and Hebrews: Profiles from the History of Interpretation, ed. Jon C. Laansma and Daniel J. Treier (New York, NY: Bloomsbury T&T Clark, 2012), 34.
 The most significant treatments I can find is Scott R. Swain, “The Radiance of the Father’s Glory: Eternal Generation, Divine Names, and Biblical Interpretation” in Retrieving Eternal Generation, 29-43; John Webster, “One Who Is Son: Theological Reflections on the Exordium of the Epistle to the Hebrews” in The Epistle to the Hebrews and Christian Theology, ed. Richard Bauckham et al (Grand Rapids: Wm. B. Eerdmans, 2009), 69–94.
 I realize that at least theoretically, other options may be possible. Present limitations constrain us to limit our survey to these three, which represent the views expressed by the vast majority of commentators.
 Scott R. Swain and Michael Allen, “The Obedience of the Eternal Son: Catholic Trinitarianism and Reformed Christology” in Christology: Ancient and Modern (Explorations in Christian Dogmatics), eds. Oliver D. Crisp and Fred Sanders (Grand Rapids: Zondervan, 2003), 75.
 Augustine of Hippo, “On the Trinity,” in St. Augustin: On the Holy Trinity, Doctrinal Treatises, Moral Treatises, ed. Philip Schaff, trans. Arthur West Haddan, vol. 3, A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church, First Series (Buffalo, NY: Christian Literature Company, 1887), 24 [Augustine, De Trinitate, 1.7.14; henceforth citations will follow this abbreviated format]. Augustine was following the catholic tradition as the Fathers similarly distinguished between theologia and oikonomia and would relegate Scriptural descriptions of Christ to one or another of these categories as a hermeneutical principle. Similarly, they would distinguish whether a particular description could be properly predicated of Christ’s divinity or humanity. See Francis M. Young, “Christological Ideas in the Greek Commentaries on the Epistle to the Hebrews,” in Laansma and Treier, 35. For numerous examples of how the Fathers applied this hermeneutic to Hebrews 1:3, see Ancient Christian Commentary on Scripture: New Testament X: Hebrews, gen. ed. Thomas C. Oden, ed. Erik M. Heen and Philip D. W. Krey (Downers Grove, IL: 2005), 10–18.
 Some argue that ontology is not in view based on other grounds, such as their allegations that Jesus is not the eternal Son but was adopted as such in his humanity. I consider such positions to be heretical and will not interact with them here, because I do not consider them to be valid options for the Christian interpreter. Whether we admit it or not, our theology/philosophy does inform our hermeneutics—and that is true even in the case of those who claim not to be ‘biased’ by any theological presuppositions. For a helpful refutation of a couple of such views, see John Webster, “One Who Is Son” in The Epistle to the Hebrews and Christian Theology, 79–80.
 Divine essence per se does not purge sin through the shedding of atoning blood, nor could it be non-ubiquitous so as to move locally from place to another.
 Douglas McCready, He Came Down From Heaven: The Preexistence of Christ and the Christian Faith (Downers Grove, IL: Intervarsity Press, 2005), 115–16.
 Vos surveys the options and favors an ontological position, because, for one, “The author speaks in terms of being, not in terms of the Son’s doing.” Geerhardus Vos, The Teaching of the Epistle to the Hebrews, ed. Johannes G. Vos (Phillipsburg, NJ: Presbyterian and Reformed Publishing, 1956), 82.
 John Owen, An Exposition of the Epistle to the Hebrews, ed. W. H. Goold, vol. 20, Works of John Owen (Edinburgh: Johnstone and Hunter, 1854), 90.
 John Owen, An Exposition of the Epistle to the Hebrews, ed. W. H. Goold, vol. 20, Works of John Owen (Edinburgh: Johnstone and Hunter, 1854), 90. This insight from Owen does not reject but further develops the insights of the Fathers whereby they would traditionally attribute each statement of Hebrews 1:1-3 either to Christ’s divine or human nature. Owen further nuances the correct interpretation of the text according to human authorial intent (i.e. grammatical-historical exegesis) and offers a strikingly coherent explanation as to why the author rapidly alternates as it were between predications of the Son in his divine and human natures. According to the communicatio idiomatum, predications of either nature of the Son may be made of his single Person. The author can speak of the Son’s Person by using alternating attributes that pertain properly to either his divine or human natures, without intending any confusion or mixture of his two distinct natures (see Acts 20:28). For a textbook explanation, see Louis Berkhof, Systematic Theology (Grand Rapids: Wm. B. Eerdmans, 1938), 324.
 Some may deny that God’s creatorhood is rooted in his ontology. I agree with James E. Dolezal as a fellow “classical eternalist” that we must “distinguish between the manner in which creatures come to name God as Creator, and the reality of creatorhood in God Himself.” Creatorhood properly pertains to ontology but extends to economy as “An Eternal Act Producing a Temporal Effect.” All That is in God: Evangelical Theology and the Challenge of Classical Christian Theism (Grand Rapids: Reformation Heritage Books, 2017), 98–100.
 Another way to say this is that these three assertions (appointment as heir, creation, and providence) build on theología and extend to oikonimía. They pertain properly to the Son “in the form of God” in the internal Godhead, but they also extend to his work in the world and incorporate all that he did “in the form of a servant.”
 The dative here may be locative, which would semantically intensify the Son’s revelation of the Father beyond that of all the other prophets. “In the Son, God speaks. In the case of the prophets, ἐν bore an instrumental sense; here its sense is more local. One might, perhaps, say ‘in and as,’ to try to catch the sense that God’s act of revelation can properly be attributed not only to Θεὸς but also to υἱός, who is, by consequence, not simply its instrumental cause.” John Webster, “One Who Is Son” in The Epistle to the Hebrews and Christian Theology, 79. Many commentators share this opinion. I think it is plausible.
 I say “generic” of the term itself, since it can refer to any deity, even pagan gods. But it is not generic when applied contextually by NT authors to the one true God. It carries the weight of a proper title that stresses the quality of divinity—implying his unrivaled supremacy and divine nature. When used of the one true God, Θεὸς implies strict monotheism; i.e. he is God and no other. Though normally applied to the Father, some passages do apply Θεὸς to the Son, showing he is the same God (John 1:1; Matt. 1:23; Rom. 9:5; Phil. 2:6; 1 Tim. 3:16 [TR]; Titus 2:13; Heb. 1:8; 1 John 5:20).
 God is inherently, necessarily, Trinitarianly, relational. Douglas F. Kelly, Systematic Theology: Grounded in Holy Scripture and Understood in the Light of the Church, vol. 1 (Ross-shire, Scotland: Mentor, 2008), 447–448.
 I.e. it is getting at the one incommunicable divine property that is unique to the Son, distinguishing him from the Father. See Turretin, Institutes, 3.23.8. There is one such property—only one. All other attributes are fully shared by both since all that the Father is, the Son is also, except that the Son is not the Father. This fact limits the divine property to which ἀπαύγασμα could be referring. If not to the Son’s begottenness/Sonship (by inference, entailing eternal generation), what other unique personal incommunicable property proper to the Son’s hypostasis could it possibly be? To assert it is a different, additional property unique to the Son would be Trinitarian heresy; to assert that the Father is the brightness just as the Son is the brightness is to undermine the text’s ascription of this “brightness” relationally, particularly, and exclusively to the Son, which would make the text redundant and nonsensical (in other words, is the Father “the express image of the Father”? No. That would be nonsense. In like manner, the Son uniquely is “the brightness of his glory.”).
 τῆς δόξης in this case is probably best understood as a genitive of source. The brightness comes from the glory; the radiance is the outshining from the glory.
 To qualify such derivation apophatically, orthodox Christology asserts that this it is (1) not creaturely, (2) not finite, (3) not imperfect, (4) not temporal, and (5) not univocal to our language. These apophatic qualifiers eschew Ariainism and all Christological subordinationism.
 In the Nicene Creed, ἐκ followed by the genitive φωτός should be understood as fontal, referring to source and derivation, like beams of light from the source of light. Its semantic force stresses co-equality. That is how the orthodox Fathers understood it, that is what they intended by it in the Creed, and all their writings bear abundant testimony to this fact. Many modern theologians claim to subscribe to the Nicene Creed, but they deny the derivation of the divine essence by its unmitigated ontological, eternal, and necessary communication from the Father to the Son. Does one really subscribe to the Creed if they merely affirm its surface language but deny the intended meaning of its words?
 The modern thinker may conceptually dissociate fire from light, but we must remember that in the ancient world, light was normally conceived of as fire and as from fire. The biblical testimony gives accommodated revelation adapted to that ancient world with its perspectival conceptions. Therefore, passages describing God as fire would most naturally convey immediate associations with light (cf. Ps. 105:39).
 Notice that in Revelation 21:23 the Lamb is the one described as “the light” and not the Father. The Father and the Lamb are the temple of the city (21:22); this city is filled with the glory of the Father and the Son; but the Son particularly is the one who manifests the radiance of the glory as its lamp (verse 23). There is clear parallel here to Hebrews 1:3 on a number of levels.
 We could also appeal to the apocryphal Wisdom of Solomon 7:25–26: “For she is a breath of the power of God, and a clear effluence of the glory of the Almighty; therefore can nothing defiled find entrance into her. For she is an effulgence from everlasting light and an unspotted mirror of the working of God, and an image of his goodness.” See Lewis Ayres, Nicaea and its Legacy: An Approach to Fourth-Century Trinitarian Theology (New York: Oxford University Press, 2004; repr. 2009), 42. There are intertextual and conceptual links between our phrase in Hebrews 1:3, God’s consubstantial Wisdom (Wisdom 7; Prov. 8:22–31), the Logos Christology of John and its Hebraic background in Proverbs 8, and μονογενής in John 1:18.
 Owen, Hebrews, ed. W. H. Goold, 20:92. While that analogy may be (wrongfully, I think) debated in Hebrews 1:3, it is quite conspicuous in Revelation 1:16, 21:23, and hinted at in Malachi 4:2. See also Thomas C. Oden, The Word of Life: Systematic Theology, Vol. II (San Francisco, CA: HarperSanFrancisco, 1992), 55–56.
 Some reject this analogy because it can lead to heresy if taken too far. But such rejection is not warranted by Scripture. Holy writ describes God by way of analogy using creaturely things and creaturely words. He is self-described by attributes proper to animals and inanimate objects. Anthropopathisms and anthropormorphisms are a case in point. Such analogies describing the ineffable deity need to be employed cautiously, but since God reveals himself in nature and Scripture, and since all of God’s self-revelation is accommodated to our finite, creaturely capacities, and since special revelation presupposes and builds upon the epistemological framework of general revelation, such analogies are fitting in expounding to us truths about God. The analogy of the sun and its beams is a good one, and I for one stand with Athanasius and the Fathers in esteeming its biblical propriety as one that is commendable and useful when employed responsibly.
 Athanasius of Alexandria, “To the Bishops of Egypt,” in St. Athanasius: Select Works and Letters, ed. Philip Schaff and Henry Wace, trans. Miles Atkinson and Archibald T. Robertson, vol. 4, A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church, Second Series (New York: Christian Literature Company, 1892), 230.
 John Owen, An Exposition of the Epistle to the Hebrews, ed. W. H. Goold, vol. 20, Works of John Owen (Edinburgh: Johnstone and Hunter, 1854), 92.
 Augustine, De Trinitate, 6.2.3.
 Scott R. Swain, “The Radiance of the Father’s Glory: Eternal Generation, the Divine Names, and Biblical Interpretation,” in Retrieving Eternal Generation, ed. Fred Sanders and Scott R. Swain (Grand Rapids: Zondervan, 2017), 41.
 This is further confirmed by the words that follow in the text, which describe the Son as “the express image of his person.” Support for this thesis can be pretty much doubled if we were to consult the additional material of this conjoined phrase, but such is beyond the scope of the present limitations for this paper.
 John M. Frame, Salvation Belongs to the Lord: An Introduction to Systematic Theology (Phillipsburg, NJ: P&R Publishing, 2006), 38.
 This phrase is borrowed from David B. Garner, Sons in the Son: The Riches and Reach of Adoption in Christ (Phillipsburg, NJ: P&R Publishing, 2016).