The reason is, that anything which is essentially wrong is worse than that which is wrong through accident.

For a man openly to bring contempt on himself is essentially wrong to his friend, because a man owes it to take account of his fault secretly, and no one is more friendly to himself than the man himself.

In the chamber of his thoughts, therefore, he should reprove himself and weep over his faults, and not before the world.

Again, a man is but seldom blamed when he has not the power or the knowledge requisite to guide himself aright: but he is always blamed when weak of will, because our good or evil dispositions are measured by the strength of will.

Wherefore he who blames himself proves that he knows his fault, while he reveals his want of goodness; if, therefore, he know his fault, let him no more speak evil of himself.