“Better that right counsels be known to enemies than that the evil secrets of tyrants should be concealed from the citizens. They who can treat secretly of the affairs of a nation have it absolutely under their authority; and as they plot against the enemy in time of war, so do they against the citizens in time of peace.”

“I should attempt to treat human vice and folly geometrically... the passions of hatred, anger, envy, and so on, considered in themselves, follow from the necessity and efficacy of nature... I shall, therefore, treat the nature and strength of the emotion in exactly the same manner, as though I were concerned with lines, planes, and solids.”

“Peace is not the absence of war, it is a virtue, a state of mind, a disposition of benevolence, confidence, justice.”

“The greatest secret of monarchic rule...is to keep men deceived and to cloak in the specious name of religion the fear by which they must be checked, so that they will fight for slavery as they would for salvation, and will think it not shameful, but a most honorable achievement, to give their life and blood that one man may have a ground for boasting.”

“He who seeks to regulate everything by law is more likely to arouse vices than to reform them. It is best to grant what cannot be abolished, even though it be in itself harmful. How many evils spring from luxury, envy, avarice, drunkenness and the like, yet these are tolerated because they cannot be prevented by legal enactments.”

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

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