170.
Repeated sin destroys the understanding
And he whose reason is impaired repeats
His sins. The constant practising of virtue
Strengthens the mental faculties, and he
Whose judgment stronger grows acts always right.
Mahābhārata.
171.
If you wish to know how much preferable wisdom is to gold, then observe: if you change gold you get silver for it, but your gold is gone; but if you exchange one sort of wisdom for another, you obtain fresh knowledge, and at the same time keep what you possessed before.
Talmud.