… it was because He had already His Son close at His side, as a second Person, His own Word, and a third Person also, the Spirit in the Word, that He purposely adopted the plural phrase, “Let us make;” and, “in our image;” and, “become as one of us.” For with whom did He make man? and to whom did He make him like? (The answer must be), the Son on the one hand, who was one day to put on human nature; and the Spirit on the other, who was to sanctify man. With these did He then speak, in the Unity of the Trinity, as with His ministers and witnesses.
But all the rest of the created things did He in like manner make, who made the former ones—I mean the Word of God, “through whom all things were made, and without whom nothing was made.” Now if He too is God, according to John, (who says,) “The Word was God,” then you have two Beings—One that commands that the thing be made, and the Other that executes the order and creates. In what sense, however, you ought to understand Him to be another, I have already explained, on the ground of Personality, not of Substance—in the way of distinction, not of division. But although I must everywhere hold one only substance in three coherent and inseparable (Persons), yet I am bound to acknowledge, from the necessity of the case, that He who issues a command is different from Him who executes it.
Tertullian
Against Praxeas
Chapter XII