Whatsoever is contrary to nature is contrary to reason, and whatsoever is contrary to reason is absurd.

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Freedom is absolutely necessary for the progress in science and the liberal arts.

It may easily come to pass that a vain man may become proud and imagine himself pleasing to all when he is in reality a universal nuisance.

All things excellent are as difficult as they are rare.

When a man is prey to his emotions, he is not his own master.

I do not know how to teach philosophy without becoming a disturber of the peace.

Fame has also this great drawback, that if we pursue it, we must direct our lives so as to please the fancy of men.

Peace is not the absence of war; it is a virtue; a state of mind; a disposition for benevolence; confidence; and justice.

If men were born free, they would, so long as they remained free, form no conception of good and evil.

Those who are believed to be most abject and humble are usually the most ambitious and envious.

He alone is free who lives with free consent under the entire guidance of reason.

So long as a man imagines that he cannot do this or that, so long as he is determined not to do it; and consequently so long as it is impossible to him that he should do it.

Whatsoever is, is in God, and without God nothing can be, or be conceived.

Peace is not an absence of war, it is a virtue, a state of mind, a disposition for benevolence, confidence, justice.

The highest activity a human being can attain is learning for understanding, because to understand is to be free.