Every achievement, every step forward in knowledge, is the consequence of courage, of toughness towards oneself, of sincerity to oneself

Man is the cruelest animal.

Just as bones, tissues, intestines, and blood vessels are enclosed in a skin that makes it possible to bear the sight of a human being, so the agitations and passions of the soul are wrapped up in vanity: it is the soul's skin.

The rights which a man arrogates to himself are relative to the duties which he sets himself, and to the tasks which he feels capable of performing.

A man of genius is unbearable, unless he possesses at least two things besides: gratitude and purity.

It is however a disgrace to pray! Not for all, but for you, and me, and whoever has his a conscience.

Spiritual strength and passion, when accompanied by bad manners, only provoke loathing.