productions cannot be in their right mind, inasmuch as they undertake to
describe things that are indescribable.
St. Ambrose of Milan, Hexameron 6, 7, 40 (post 389 AD)
But let us consider the course of our own creation. He says: Let Us make
man to our image and to our likeness. Who says this? Is it not God, who
made you? ... To whom does He say it? Certainly not to Himself, for He
does not say Let Me make but Let Us make. Nor to the Angels, for they
are ministers; and servants can have no partnership in the operation of the
master, nor works with their author. It is the Son to whom He speaks, even
if the Jews will not have it and the Arians fight against it ... [And it is the
Son] who is the image of God the Father, the Son who always is and who
was in the beginning.
St. Augustine of Hippo, The Trinity Bk. 7, Ch. 4 (inter 400-416 AD)
For that which must be understood of persons according to our usage, this
is to be understood of hypostases according to the Greek usage; for they
say three hypostases, one essence, in the same way as we say three persons,
one essence or substance.
Catechism of the Council of Trent (1566)
Pt. I, Ch. II: Since nowhere is a too curious inquiry more dangerous, or
error more fatal, than in the knowledge and exposition of this, the most
profound and difficult of mysteries...
But these truths which should not be made the subject of too subtle
investigation, when we recollect that he who is a searcher of majesty shall
be overwhelmed by glory. We should be satisfied with the assurance and
certitude which faith gives us that we have been taught these truths by God
Himself, to doubt whose word is the extreme of folly and misery. He has
said: Teach ye all nations, baptizing them in the name of the Father, and of
the Son, and of the Holy Ghost; and again, there are three who give
testimony in heaven, the Father, the Word, and the Holy Ghost; and these
three are one.