“Nothing was or is farther from my intentions, than to enlist myself as the champion of a fixed opinion, where I have only expressed doubt.”

“As new discoveries are made, new truths discovered and manners and opinions change with the change of circumstances, institutions must advance also to keep pace with the times.”

“I have the consolation of having added nothing to my private fortune during my public service, and of retiring with hands clean as they are empty.”

“With your talents and industry, with science, and that steadfast honesty, which eternally pursues right, regardless of consequences, you may promise yourself everything but health, without which there is no happiness.”

“I write nothing for publication, and last of all things should it be on the subject of religion. On the dogmas of religion as distinguished from moral principles, all mankind, from the beginning of the world to this day, have been quarrelling, fighting, burning and torturing one another, for abstractions unintelligible to themselves and to all others, and absolutely beyond the comprehension of the human mind. Were I to enter on that arena, I should only add an unit to the number of Bedlamites.

“The contest is not between Us and Them, but between Good and Evil, and if those who would fight Evil adopt the ways of Evil, Evil wins.”

“Speaking one day to Monsieur de Buffon, on the present ardor of chemical inquiry, he affected to consider chemistry but as cookery, and to place the toils of the laboratory on the footing with those of the kitchen. I think it, on the contrary, among the most useful of sciences, and big with future discoveries for the utility and safety of the human race.”

“I am increasingly persuaded that the earth belongs exclusively to the living and that one generation has no more right to bind another to it's laws and judgments than one independent nation has the right to command another.”

“Experience hath shewn, that even under the best forms, those entrusted with power have, in time, and by slow operations, perverted it into tyranny; and it is believed that the most effectual means of preventing this would be, to illuminate, as far as practicable, the minds of the people at large...”

“That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.”

“I set out on this ground, which I suppose to be self-evident, that the earth belongs in usufruct to the living.”

“The majority, oppressing an individual, is guilty of a crime, abuses its strength, and by acting on the law of the strongest breaks up the foundations of society.”

“Some men look at constitutions with sanctimonious reverence, and deem them like the ark of the covenant, too sacred to be touched. They ascribe to the men of the preceding age a wisdom more than human, and suppose what they did to be beyond amendment. I knew that age well; I belonged to it, and labored with it. It deserved well of its country. It was very like the present, but without the experience of the present; and forty years of experience in government is worth a century of book-reading; and this they would say themselves, were they to rise from the dead. I am certainly not an advocate for frequent and untried changes in laws and constitutions. I think moderate imperfections had better be borne with; because, when once known, we accommodate ourselves to them, and find practical means of correcting their ill effects. But I know also, that laws and institutions must go hand in hand with the progress of the human mind. As that becomes more developed, more enlightened, as new discoveries are made, new truths disclosed, and manners and opinions change with the change of circumstances, institutions must advance also, and keep pace with the times. We might as well require a man to wear still the coat which fitted him when a boy, as civilized society to remain ever under the regimen of their barbarous ancestors.” 

“That one generation of men in civil society have no right to make acts to bind another, is a truth that cannot be confused.”

“I have lived temperately, eating little animal food, and that not as an aliment, so much as a condiment for the vegetables, which constitute my principal diet.”