The one who acts is always without conscience; nobody has a conscience but the contemplative person.

I am the Spirit that denies.

As soon as you are in a social setting, you better take away the key to the lock of your heart and pocket it; those who leave thekey in the lock are fools.

Insofar as he makes use of his healthy senses, man himself is the best and most exact scientific instrument possible. The greatest misfortune of modern physics is that its experiments have been set apart from man, as it were, physics refuses to recognize nature in anything not shown by artificial instruments, and even uses this as a measure of its accomplishments.

Woe to him who would ascribe something like reason to Chance, and make a religion of surrendering to it.

The highest happiness of man ... is to have probed what is knowable and quietly to revere what is unknowable.

But when all is said, the greatest art is to limit and isolate oneself.