>"We say that gold, even though it be cut into many figures, is one, and is so spoken of, but we speak of many coins or many staters, without finding any multiplication of the nature of gold by the number of staters; and for this reason we speak of gold, when it is contemplated in greater bulk, either in plate or in coin, as much, but we do not speak of it as many golds on account of the multitude of the material — except when one says there are many gold pieces (Darics, for instance, or staters), in which case it is not the material, but the pieces of money to which the significance of number applies: indeed, properly, we should not call them gold but golden.
As, then, the golden staters are many, but the gold is one, so too those who are exhibited to us severally in the nature of man, as Peter, James, and John, are many, yet the man in them is one. [...] This is the cause why it says, the Lord our God is one Lord Deuteronomy 6:4, and also proclaims the Only-begotten God by the name of Godhead, without dividing the Unity into a dual signification, so as to call the Father and the Son two Gods, although each is proclaimed by the holy writers as God. The Father is God: the Son is God: and yet by the same proclamation God is One, because no difference either of nature or of operation is contemplated in the Godhead. For if (according to the idea of those who have been led astray) the nature of the Holy Trinity were diverse, the number would by consequence be extended to a plurality of Gods, being divided according to the diversity of essence in the subjects. But since the Divine, single, and unchanging nature, that it may be one, rejects all diversity in essence, it does not admit in its own case the signification of multitude; but as it is called one nature, so it is called in the singular by all its other names."
- St. Gregory of Nyssa, "On Not Three Gods" to Ablabius
https://www.newadvent.org/fathers/2905.htm
