Sin, also for those who don't have faith, exists when one goes against one's conscience. To listen to and obey it means, in fact, to decide in face of what is perceived as good or evil. And on this decision pivots the goodness or malice of our action.

A good heart is the sun and the moon; or, rather, the sun and not the moon, for it shines bright and never changes.

One must repay good and ill; but why just to the person who did us good or ill?

The good displeases us when we are not up to it.

For our self respect depends upon our ability to make requital, for good or for evil.

Just as a line drawn on water with a stick will quickly vanish and will not last long; even so is human life like a line drawn on water. It is short, limited, and brief; it is full of suffering, full of tribulation. This one should wisely understand, one should do good and live a pure life; for none who is born can escape death.