I am part of the part that once was everything, Part of the darkness which gave birth to light… Mephistopheles, from Faust.

When I consider the narrow limits within which our active and inquiring faculties are confined; when I see how all our energies are wasted in providing for mere necessities, which again have no further end than to prolong a wretched existence; and then that all our satisfaction concerning certain subjects of investigation ends in nothing better than a passive resignation... when I consider all this... I am silent.

So, lively brisk old fellow, don't let age get you down. White hairs or not, you can still be a lover.

Nature has neither core nor skin: she’s both at once outside and in.

The greatest act of faith takes place when a man finally decides that he is not God.

Fools and wise men are equally harmless. It is the half-fools and half-wise that are dangerous.

God could cause us considerable embarrassment by revealing all the secrets of nature to us: we should not know what to do for sheer apathy and boredom.