Nature, Substance, Essence
The terms “nature,” “substance,” and “essence” all signify the same thing when speaking of the being of God in Trinitarian nomenclature. We’ve previously mentioned the occasional confusion of “substance” and “person” (because of the meaning of hypostasis), and there is similar confusion in the possibility of distinguishing between “substance” and “essence,” however, the terms were eventually worked out into a consistent fashion. Though “substance” and “essence” could mean different things when speaking of the creation, they meant the same when speaking of God. Each word signified the single divine being.
Like we saw with “person,” the actual definition of these terms is quite bare. Esse means “the act of existing.” Essentia means “the whatness of a being.” Natura also means essentia or quidditas: “the character of something.” Substantia could have the connotation of material “stuff,” but in Trinitarian nomenclature it was always identified with the essence and thus spiritual, invisible, simple, and infinite.
John Locke famously defined substance as “I know not what.” In expressing it this way, he was not actually adding anything to the Christian tradition. Gregory of Nyssa proclaimed that you could not know any essence/nature. You could know about them, but you could not know them. Nevertheless, he still went on to speak of the divine essence, acquiring knowledge of it from its attributes, and he had no problem saying that the divine nature was “single” (Against Eunomius 1.19).
Augustine likewise believed that substance admitted of a vague and bare definition amounting to little more than “existence”:
…all these things are substances, simply in virtue of the fact that they exist. Their natures are called substances. God too is a certain sort of substance, for anything that is not a substance is not anything at all. A substance is something that is. (Commentary on Psalm 68.5, quoted from Lewis Ayres’ Augustine and the Trinity p 200 )
In the 7th book of De Trinitate Augustine explains that God is more properly termed essence than substance because substance can imply something that obtains its being from something else (as a composite), but that God is eternal and self-subsisting. Therefore “essence” was the better term. Either way, Augustine is getting at the same thing.
Augustine also adds that the divine essence is id ipsum, which means “self-same” or “identical.” Augustine clarifies for us by saying:
What is Idipsum? Idipsum. What can I say other than Idipsum?… What is Idipsum? That which always is in the same way, which is not now one thing, now another. What, therefore is Idipsum, unless that which is? What is that which is? That which is eternal. For that which is always one thing and then another is not, because it does not abide… (Commentary on Psalm 121.5, quoted from Ayres’ Augustine and the Trinity p 202)
This sort of discussion ought to show that the terms “substance,” “essence,” and “nature,” simply referred to God’s manner of existence, and they were always fairly resigned as far as adequacy is concerned. They were only a way to speak of the quality of God’s existence and to refer to God qua God, which is to say eternal, immortal, immutable, self-existing, etc. The “attributes” of God are all attributes of His nature. This usage of terms would continue through Anselm, Lombard, Thomas, and Calvin in a fairly consistent manner. Certain additional observations would be made, with extra questions being answered, but there would be no significant discontinuity in thought. And it was made clear in the cases of Lombard and Calvin that the divine nature never existed apart from the three persons.
That last concern has arisen again and again over church history. It is heard ubiquitously in our modern context as well, however it is usually not admitted that the charge has been answered. Instead, the charge itself is seen as enough to swear off all speaking of a divine nature, substance, or essence. Such is the state of the modern “social Trinitarian” and “personalist” theologies of our day. We can say a few things in response:
1) The Bible itself speaks of a divine nature. Many of the classical expositors based their writings off of the divine name (I AM), and even if we differ with their exegesis, such an expression is an odd “name” in the regular sense. Further, we see the divine nature referenced in Acts 17:29 and 2 Peter 1:4, as well as every instance of the term “godhead” (Romans 1:20, Col. 2:9).
2) All of the orthodox theologians were comfortable speaking of the divine being. They admitted that it was ineffable on the ultimate level, but they could still say much about it, including that it was single. The folks who did not want to allow any functional use of “substance” or “nature” were the heretics. The “Homoeans” got their name from simply dropping the “ousia” from conversation. Later, the neo-Arians like Samuel Clarke made the same argument: “essence” is a non-biblical category and should be avoided. Yet they only managed to propose heresy as an alternative. Time and time again, “essence” was defended by the orthodox, and it has proved to be an inescapable category in combating various forms of polytheism and subordination. To suggest that it is an improper concept is neither new nor helpful.
3) Denying the legitimacy of “nature” in Trinitarian nomenclature actually does gut the logic of Nicaea. According to the Nicene organization, the Father begets the Son of his own eternal being, and the Son is able to be co-equal with God in every way because He also possesses this being, which is infinite, eternal, simple, and etc. In other words, the divine nature is that which is begotten in its own act of begetting, and it is by definition eternal and unchangeable. In other words, God begets God from God. The logic of this formula will become increasingly clearer as we examine the attributes of God in the installments to come.