In Peter Lombard's Sentences Book 1 and Chapter 10 we read words like these mostly from Ambrose
You ask me, how he can be a son if he has not a prior father? I ask of you also, when or how you think the Son is generated? For to me it is impossible to know the secret of generation; the mind fails, the voice is silent; and not mine only, but that of the angels; it is above angels, above powers, above cherubim, above seraphim, and above all understanding, if the peace of Christ is above all understanding (Phil, 4:7), must not such a generation be above all understanding?
Cover then (like the angels) your face with your hands, for it is not given you to look into surpassing mysteries! We are suffered to know that the Son is begotten, not to dispute upon the manner of His begetting. I cannot deny the one; the other I fear to search into, for if Paul says that the words which he heard when caught up into the third heaven might not be uttered, 2 Corinthians 12:2-5 how can we explain the secret of this generation from and of the Father, which we can neither hear nor attain to with our understanding?