The number seventy-seven is significant.
But why does the number seventy-seven encompass all sins which are forgiven in Baptism? This probable reason seems to come forth because the number ten holds the perfection of justice and happiness when the sevenfold creature adheres to the Trinity of the Creator; hence also the Decalogue of the Law is consecrated in ten commandments. However, the transgression of the ten is signified by the number eleven, and sin is understood to be a transgression when a man, desiring something more, exceeds the rule of justice. Therefore, the Apostle calls avarice the root of all evils. And to the soul fornicating from God, it is said in the person of the Lord: "You hoped that if you departed from me, you would have something more." Therefore, because the transgression, that is, sin, pertains to the one who sins, because he wishes to rejoice in something private to himself; hence those who seek their own, not the things of Jesus Christ, are also reproached, and charity not seeking its own is praised. Therefore, the number eleven itself, by which transgression is signified, is not multiplied ten times, but seven times, and it becomes seventy-seven. For the transgression pertains not to the Trinity of the Creator, but to the creature itself, that is, to man himself, whom the number seven signifies. Three for the soul, where there is a certain image of the Trinity of the Creator; for man was made in the image of God there: and four for the body. For the four beginnings from which the body consists are very well known. And to whom they are not known, he can easily notice that the body of the world itself, in which our body moves through places, has four main parts, which even the divine Scripture continuously mentions: East and West, South and North.
And since sins are committed either in the mind, as in the will alone; or also in the works of the body, already visibly: therefore Prophet Amos continuously mentions God threatening and saying: In three and four iniquities I will not turn away, that is, I will not ignore. Three, on account of the mind; four, on account of the nature of the body: by which two man consists.
How the Holy Scriptures are to be read.
Therefore, eleven times seven, as it is said, the transgression of justice related to the sinful man makes the number seventy-seven; by which all sins are signified, which are forgiven through Baptism. Whence Luke ascends to God through seventy-seven generations; showing the reconciliation of man to God through the abolition of all sins. Then the Lord himself answered Peter questioning how many times he should forgive his brother: I say to you, he said, not seven times, but up to seventy-seven times. And if anything else can be revealed about these secrets and treasures of the mysteries of God by those who are more diligent and worthy. However, as much as our capacity allows, as much as the Lord has helped and given, and also considering the constraint of time, we have said what we could. If any of you can grasp more, knock at the one from whom we also receive what we can grasp and speak. Above all, keep this: do not be disturbed by the Holy Scriptures not yet understood; and when understood, do not be arrogant: but what you do not understand, defer with honor; and what you understand, hold with love.