1 I have shown that the number thirty fails them in every respect; too few Æons, as they represent them, being at one time found within the Pleroma, and then again too many [to correspond with that number]. There are not, therefore, thirty Æons, nor did the Saviour come to be baptized when He was thirty years old, for this reason, that He might show forth the thirty silent Æons of their system, otherwise they must first of all separate and eject [the Saviour] Himself from the Pleroma of all.
Moreover, they affirm that He suffered in the twelfth month, so that He continued to preach for one year after His baptism; and they endeavour to establish this point out of the prophet (for it is written, “To proclaim the acceptable year of the Lord, and the day of retribution”), being truly blind, inasmuch as they affirm they have found out the mysteries of Bythus, yet not understanding that which is called by Isaiah the acceptable year of the Lord, nor the day of retribution.
For the prophet neither speaks concerning a day which includes the space of twelve hours, nor of a year the length of which is twelve months. For even they themselves acknowledge that the prophets have very often expressed themselves in parables and allegories, and [are] not [to be understood] according to the mere sound of the words.
Source: Adversus haereses (New Advent)