38 But this divine discourse has not left our understandings unenlightened, since it explains the reason of the phrase in what follows:— God made the regions, both the uninhabitable parts and the heights which are inhabited under the heaven. When He was preparing the heaven, I was with Him; and when He was setting apart His own seat. When above the winds He made the clouds huge in the upper air, and when He placed securely the springs under the heaven, and when He made firm the foundations of the earth, I was by Him, joining all things together. What period in time is here?
Or how far are the conceptions of human intelligence allowed to reach beyond the infinite birth of God Only-begotten? By means of things whose creation we can conceive in our mind, it is not possible to understand the generation of Him, Who is prior to all these things; and hence we cannot maintain that He came, indeed, first in time, yet was not infinite, inasmuch as the only privilege bestowed upon Him was a birth prior to things temporal. For in that case, since they, by their constitution, are subject to the conditions of time, He, though prior to them all, would be equally subject to conditions of time, because their creation within time would define the time of His birth, namely that He was born before then; for that which is antecedent to temporal things stands in the same relation to time as they.
Source: On the Trinity (New Advent)