To be able to speak about things exalted, we need to begin with the Father, who is the root of everything. From him, we have received grace to speak about him. He existed before anything other than himself came into being. The Father is a single one, like a number, for he is the first one and the one who is only himself. Yet he is not like a solitary individual. Otherwise, how could he be a father? For whenever there is a "father," the name "son" follows. But the single one, who alone is the Father, is like a root with a tree, branches, and fruit.
The Tripartite Tractate 51.1-20 (Valentinian, end of second century)
Comment: Note how the language and the topic of discussion is part of a dialogue among the second century church theologians about the nature of the Father and his relationship with the Son. The metaphor used is common among the theologians at this time, and is used by Tertullian in order to argue for three persona and one substantia in an oikonomia when he takes on Modalism.