“I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical.” 

“I believe that banking institutions are more dangerous to our liberties than standing armies.” 

“Ridicule is the only weapon which can be used against unintelligible propositions.”

“The constitution of most of the states (and of the United States) assert that all power is inherent in the people; that they may exercise it by themselves; that it is their right and duty to be at all times armed and that they are entitled to freedom of person, freedom of religion, freedom of property, and freedom of the press.”

“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.” 

“I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend.” 

“[T]he artillery of the press has been leveled against us, charged with whatsoever its licentiousness could devise or dare. These abuses of an institution so important to freedom and science are deeply to be regretted...”

“The vote being passed, altho' further observn on it was out of order, he could not refrain from rising and expressing his satisfaction and concluded by saying "there is but one word, Mr. President, in the paper which I disapprove, & that is the word Congress," on which Ben Harrison rose and said "there is but on word in the paper, Mr. President, of which I approve, and that is the word Congress.”

“I never submitted the whole system of my opinions to the creed of any party of men whatever in religion, in philosophy, in politics, or in anything else where I was capable of thinking for myself. Such an addiction is the last degradation of a free and moral agent. If I could not go to heaven but with a party, I would not go there at all.”

“The attempt of Lavoisier to reform chemical nomenclature is premature. One single experiment may destroy the whole filiation of his terms; and his string of sulphates, sulphites, and sulphures, may have served no end than to have retarded the progress of science by a jargon, from the confusion of which time will be requisite to extricate us.” 

“I have examined all the known superstitions of the world,and I do not find in our particular superstition of Christianity one redeeming feature. They are all alike founded on fables and mythology. Millions of innocent men women and children since the introduction of Christianity,have been burnt, tortured, fined and imprisoned. What has been the effect of this coercion? To make one half the world fools and the other half hypocrites; to support roguery and error all over the earth.”

“A great deal of love given to a few is better than a little to many.”

“I have indeed two great measures at heart, without which no republic can maintain itself in strength: 1. That of general education, to enable every man to judge for himself what will secure or endanger his freedom. 2. To divide every county into hundreds, of such size that all the children of each will be within reach of a central school in it”

“He who knows best knows how little he knows.”

“The object most interesting to me for the residue of my life, will be to see you both developing daily those principles of virtue and goodness which will make you valuable to others and happy in yourselves, and acquiring those talents and that degree of science which will guard you at all times against ennui, the most dangerous poison of life. A mind always employed is always happy. This is the true secret, the grand recipe for felicity....In a world which furnishes so many employments which are useful, and so many which are amusing, it is our own fault if we ever know what ennui is...”