What did Tertullian say about the trinity?

Tertullian, answered from the texts and cited to the page.

Tertullian answers

I say that God is one, and that this one God has a Son, His Word, who proceeded from Himself, by whom all things were made, and without whom nothing was made. This I hold under a dispensation, an oikonomia, and I hold it as the faith that has come down from the beginning of the gospel, before the older heresies, much more before Praxeas, a pretender of yesterday.¹

The Unity is distributed into a Trinity, and the three Persons stand in their order: Father, Son and Holy Ghost. They are three not in condition but in degree, not in substance but in form, not in power but in aspect. They are of one substance, one condition and one power, because there is one God from whom these degrees and forms and aspects are reckoned.²

I will not have the three taken for one and the same Person. Praxeas supposed that one cannot believe in One Only God unless the Father, Son and Spirit are the selfsame Person, and so he made the Father be born and suffer.¹ The rule I profess is that the Father is one, the Son one, the Spirit one, and that they are distinct from each other. The distinction is by distribution, not diversity; by distinction, not division.

For the Father is the entire substance, and the Son a derivation and portion of the whole. The names themselves testify to this, since He who begets is one and He who is begotten another, He who sends one and He who is sent another.³ I reasoned from nature. God sent forth the Word as the root puts forth the tree, the fountain the river, the sun the ray.

These are emanations of the substances from which they proceed. The tree is not severed from the root, nor the ray from the sun, nor the Word from God. So I call the Father and the Son two, as root and tree are two things joined, as sun and ray are two forms of one undivided substance. Whatever proceeds from another must be second to it without being separated; where there is a second there are two, and where there is a third there are three.

The Spirit is third from God and the Son, as the fruit is third from the root. The Trinity flows down from the Father through connected steps and does not disturb the Monarchy, while it guards the Economy.⁴ I would give the name sun even to the beam considered by itself; but when I speak of the sun from which the ray goes forth, I withdraw the name from the beam.

I make not two suns, yet two things, two forms of one undivided substance.⁵ As for worship, once Christ came and was recognised as the one who from the beginning had caused plurality, second from the Father and with the Spirit the third, the title of God and Lord was restored to the Unity. The Gentiles had to pass from the crowd of their idols to the One God, and Christians must not swear by a plurality of gods and lords.

Otherwise we should quench our torches and lose our courage for the martyr's sufferings.⁵ So I follow the apostle: where Father and Son are named together, I call the Father God and invoke Jesus Christ as Lord, but when Christ is named alone I may call Him God.⁵

Sources

believe that there is one only God, but under the following dispensation, or oi0konomi/a, as it is called, that this one only God has also a Son, His Word, who proceeded from Himself, by whom all things were made, and without whom nothing was made.
Against Praxeas
three, however, not in condition, but in degree; not in substance, but in form; not in power, but in aspect; yet of one substance, and of one condition, and of one power, inasmuch as He is one God
Against Praxeas
the Father is the entire substance, but the Son is a derivation and portion of the whole
Against Praxeas
Following, therefore, the form of these analogies, I confess that I call God and His Word-the Father and His Son-two.
Against Praxeas
I make not two suns, still I shall reckon both the sun and its ray to be as much two things and two forms of one undivided substance, as God and His Word, as the Father and the Son.
Against Praxeas