The church has employed many terms, with reference to the Father, to distinguish the Father from the other two persons of the Trinity. This is not to say that the Father may be distinguished in many ways from the other two, but rather, it is to say that there are different ways in speaking of the personal property of the Father that distinguishes him from the Son and the Spirit. Some of those terms that we will be covering include: principle, source, fons divinitatis, and auctor. These terms signify that the Father is the origin of the other two while having no origin from another. That is, he communicates the divine essence to the Son through eternal generation, and he does likewise together with the Son to the Spirit through spiration while he himself does not receive a communication of the divine essence from another person. The following will attempt to clarify these terms in understanding the Father as the origin of the others while having no origin from another.
Statement of Finitude and Difficulty in Language
Before going into an exposition on the person of the Father, we must humbly confess that we are incompetent creatures and God is the infinite Creator. Our knowledge is ectypal (incomplete) and we are attempting to understand the archetype (complete originator). In attempting to know the one called, “Father,” we are surely prone to have in mind earthly fathers and draw creaturely analogies. While analogy is definitely there, we must maintain the Creator-creature distinction. Therefore, especially with reference to the Father, since there are so many terms that we can ascribe to the Father, we must be careful not to ascribe or carry too much creaturely meaning in applying them to him. As will be seen, human terminology in describing any of the persons is difficult. Much thought and care must go into applying terms to the Father (and the other persons). In doing so, one can then understand the Father’s relation to the other two persons and identify his personal property.
Terms for the Father: Principle, Fons Divinitatis, and Auctor
To begin, we shall present what the Father does in relation to the other two persons. Eternally, the Father begets the Son in which the Son is from the Father and the Father is father to the Son. Further, together with the Son, the Father acts in spirating (breathing out) the Spirit. In this, the work with the Son of spiration and the work of the Father begetting the Son “identify the Father as the principle or fontal [think “fount”] source of the Son and (with the Son) of the Spirit.”
Principle, here, “simply designates the reality from which something else proceeds.” In other words, principle refers to the origin of another, that is, where/who they proceed from. With this in mind, another term, “fons” (source or fount), which aids in capturing the notion of principle, becomes helpful in showing where the other two persons find their origin. Because the Father is the principle of the other two, he is the fons divinitatis, fount of divinity.
This means that the other two divine persons, Son and Spirit, receive everything they are from the Father (the Spirit is from the Father and the Son who act as one principle source of the Spirit). Being the source or principle of the Son and of the Spirit (with the Son), it follows that the Father is a nemine—from no one and thus, he is innascible (unbegotten, or ungenerated, or not being “from another”). With knowledge of the Father being principle and a nemine (from no one), when describing the Father, one can thus also use the term or name, “auctor” or auctoritas (author, originator) which “denotes the principle which does not derive its being from another.” In this sense, the Father is the fons divinitatis (fount of divinity) that does not flow forth from another because he is the principle without principle, that is, auctoritas, source without source. However, there may be some danger in employing the term “auctor” and “fons divinitatis.
In employing the term, “auctor,” there may be some etymological baggage. With this in mind, one can derive hierarchical connotations of ontological superiority. This connotation also may be present in the term, “fons divinitatis.” For one could take it as one who generates divinity. However, as auctor or fontal source of divinity (fons divinitatis), the Father’s status has no ontological superiority or priority. There is no ontological hierarchy in the Trinity, none whatsoever. So what then do we mean when we employ terms such as “auctor” and “fons divinitatis?” In regards to the former, Emery says with the help of Aquinas:
St Thomas explains that the name auctor denotes the principle which does not derive its being from another: “This is why, even though the Son can be called principle [of the Holy Spirit], only the Father is named auctor.” The name auctor thus denotes the relation of principle found in the person of the Father. It just indicates the relation through which the Father is the source of the Son, without implying any inferiority to him.
In regards to the latter, fons divinitatis does not mean that the Father generates the divine essence (the divine essence cannot be generated [Exod 3:14]!). Rather, it is to say that the Father is the source of the divine persons. As Köstenberger and Swain write: “The Son and the Spirit, as concrete persons, are ‘from the Father.’ The Father, in other words, is the ‘font’ of persons who are divine. However, those persons, with the Father, fully possess the identical, self existent (underived, ungenerated) divine essence of the Father.” While using these terms in the right sense are theologically helpful and accurate, they can be horribly misunderstood. This is why I believe that principle is most appropriate to employ in our fallen, finite, human language (at least in English).
When we use the term, “principle,” we can actually mean the same thing “‘in which there is no difference of this kind, but merely one based on some sort of order;’” that is, a difference not of nature or essence, but one of order of origin, which is the only way a person can be distinguished—through the relations of origin. Therefore, “We must speak of the Father as a ‘principle without priority.’” Again, and I am firm about this, there is no ontological hierarchy in the Trinity. With this in mind, the term, “principle,” seems most appropriate given semantic or etymological dangers and baggage with the other terms. This is not to say that the other terms are wrong or faulty, but rather, it is to say that we believe that the term, “principle,” has the least unnecessary baggage while being theologically accurate. From here, one can then move to identifying the personal property of the Father.
The Personal Property of the Father
In attempting to identify the Father’s personal property, one may attempt to ascribe three: spiration, unbegottenness (innascibility), and paternity. However, in considering a personal property, one must understand the difference between that which is common, and that which is proper (personal). That which is proper belongs only to one particular person. This is what constitutes a person as a person in relation, and so signifies a distinction of “this one” from the other two. With this in mind, spiration (the act of breathing out the Spirit) must be eliminated from these selections above because it “is common to the Father and the Son who eternally breathe forth the Spirit as from one principle.” In other words, spiration can be ascribed as a characteristic (or notion) of many persons—the Father and the Son.
Second, one may attempt to ascribe “unbegottenness” as the Father’s personal property. While it is true that only the Father does not proceed from another person through a relation of origin, the fact that God is a nemine (from no one) or unbegotten is not a relational feature; instead, it is just a denial of a one. In other words, speaking of God the Father as a nemine or unbegotten is “more of a statement of what he is not….”
All that is left for us to ascribe to the Father then is paternity (fatherhood). Only the Father eternally begets the Son and is thus father to the Son. Therefore, the personal property of the Father is paternity. Now paternity can be summarized as this: it is that which belongs to and only to the Father wherein he relates to the Son as source of the Son, that is, “the relation according to which the Father is the source of the Son; in an act be which, in the identity of the substance, he vitally communicates to him the fullness of divinity.” Further, as Emery adds, “The Father as Father thus communicates to his Son the whole treasure of divinity, except for the fact of being Father which, precisely, indicates his relation to the Son.” Put simply, the personal property of the Father is him being the source as Father of the person of the Son through eternal generation. Therefore, the name “Father” (πατηρ; pater) is not only fitting for the first person of the Trinity, but it is proper because paternity is the personal property of the Father.
Summary of the Father
In summary of what we have presented, the Father is the one who is principle of the other two—the origin of the others—while being a nemine from no one. In other words, he is the source of the other two divine persons: the fons divinitatis. With this in mind, then, he necessarily is the principle without principle, source without source. While one may naturally presuppose ontological hierarchy here, there is no superiority with reference to essence in the Trinity. Finally, as shown above, because only the Father is the origin of the Son and is thus father to the Son through eternal generation, then the personal property of the Father, that which distinguishes him from the other two, is paternity. From here, one can move to the second person: the eternal Son.
 Scott R. Swain, “Divine Trinity,” in Christian Dogmatics: Reformed Theology for the Church Catholic (Grand Rapids: Baker, 2016), 99.
 Emery, The Trinitarian Theology of St Thomas Aquinas, 157.
 Aquinas, ST, 1.33.1.
 Emery, The Trinitarian Theology of St Thomas Aquinas, 159. Emery also writes, “The Father’s character is equally well designated by auctor as by principle, and by the cognate term auctoritas” (ibid., 158).
 Ibid., 159, Emery quotes Aquinas, I Sent. d. 29, q. 1, a. 1 (brackets Emery’s).
 Andreas J. Köstenberger and Scott R. Swain, Father, Son, and Spirit: The Trinity and John’s Gospel, New Studies in Biblical Theology (Downers Grove, IL: InterVarsity Press, 2008), 184.
 This, however, is not to say that the term, “principle,” captures the depth of the Father, nor do we mean that it has no baggage.
 Emery, The Trinitarian Theology of St Thomas Aquinas (London: Oxford University Press, 2010), 158, quote of Aquinas, ST, 1.33.1.
 Swain, “Divine Trinity,” 99.
 Ibid., 98n78.
 Ibid., 98n78.
 Ibid., 99.
 Emery, The Trinitarian Theology of St Thomas Aquinas, 153.
 Ibid., 156.