35 So, then, seven times eleven, that is, as has been explained, the transgression of righteousness, which has regard only to the sinner himself, make up the number seventy-seven, in which it is signified, that all sins which are remitted in Baptism are contained. And hence it is that Luke ascends up through seventy-seven generations unto God, as showing that man is reconciled unto God by the abolition of all sin. Hence the Lord Himself says to Peter, who asked Him how oft he ought to forgive a brother, “I say not unto you seven times, but until seventy times and seven.” Now, whatever else can be drawn out of these recesses and treasures of God's mysteries by those who are more diligent and more worthy than I, receive.
Yet have I spoken according to my poor ability, as the Lord has aided and given me power, and as I best could, considering also the little time I had. If any one of you be capable of anything further, let him knock at Him from whom I too receive what I am able to receive and speak. But, above all things, remember this; not to be disturbed by the Scriptures, which you do not yet understand, nor be puffed up by what you do understand; but what you do not understand, with submission wait for, and what you do understand, hold fast with charity.
Source: Sermons on Selected Lessons of the New Testament (New Advent)