Than the beginning is there nothing older, if it have, retained to itself, the definition of the beginning (for a beginning of beginning there cannot be); or it will wholly depart from being in truth a beginning, if something else be imagined before it and arise before it. Otherwise, if anything can precede what is truly beginning, our language respecting it will go off to infinity, another beginning ever cropping up before, and making second the one under investigation.
There will then be no beginning of beginning, according to exact and true reasoning, but the account of it will recede unto the long-extended and incomprehensive. And since its ever-backward flight has no terminus, and reaches up to the limit of the ages, the Son will be found to have been not made in time, but rather invisibly existing with the Father: for in the beginning was He. But if He was in the beginning, what mind, tell me, can over-leap the force of the was? when will the was stay as at its terminus, seeing that it ever runs before the pursuing reasoning, and springs forward before the conception that follows it?
Astonishment-stricken whereat the Prophet Isaiah says, Who shall declare His generation? for His Life is lifted from the earth. For verily lifted from the earth is the tale of the generation of the Only-Begotten, that is, it is above all understanding of those who are on the earth and above all reason, so as to be in short inexplicable. But if it is above our mind and speech, how will He be originate, seeing that our understanding is not powerless to clearly define both as to time and manner things originate?
Cyril of Alexandria. (1874). Commentary on the Gospel according to S. John, Volume 1 (11–12). Oxford; London: James Parker & Co.; Rivingtons.