And one cried unto another, and said, Holy, holy, holy, is the LORD of hosts: the whole earth is full of his glory.
All Commentaries on Isaiah 6:3 Go To Isaiah 6
Fulgentius of Ruspe
AD 533
The prophet Isaiah did not keep silent about this Trinity of persons and unity of nature revealed to him, when he says he saw the seraphim crying out, “Holy, holy, holy, Lord God of hosts.” Therefore, where the triple “holy” is repeated, there is the Trinity of persons; where “God Lord of hosts” is said but once, we recognize the unity of the divine nature. Therefore, in that Holy Trinity—and I keep on saying it so that it may be fixed in your heart the more firmly—the Father is one, who alone by his nature has generated the one Son from himself; and the Son is one, who alone has been born from the nature of the one Father; and the Holy Spirit is one, who alone proceeds from the essence of the Father and the Son. All of this is not possible for one person, that is, to generate oneself and to be born of oneself and to proceed from oneself. Therefore, because generating is different from being born and proceeding is something different again from generating and being born, it is obvious that the Father is different, the Son is different, and the Holy Spirit is different. The Trinity, therefore, refers to the persons of the Father and the Son and the Holy Spirit; unity, to the nature.
