They do not think, therefore they are not.

If there were only turnips and potatoes in the world, someone would complain that plants grow the wrong way.

We have to believe that everything has a cause, as the spider spins its web in order to catch flies. But it does this before it knows there are such things as flies.

He was then in his fifty-fourth year, when even in the case of poets reason and passion begin to discuss a peace treaty and usually conclude it not very long afterwards.

Sickness is mankind's greatest defect.

The writer who cannot sometimes throw away a thought about which another man would have written dissertations, without worry whether or not the reader will find it, will never become a great writer.

Be attentive, feel nothing in vain, measure and compare: this is the whole law of philosophy.