“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.” 

“No government ought to be without censors; and where the press is free no one ever will.”

“But every difference of opinion is not a difference of principle.”

“Bigotry is the disease of ignorance, of morbid minds; enthusiasm of the free and buoyant. Education and free discussion are the antidotes of both. We are destined to be a barrier against the returns of ignorance and barbarism. Old Europe will have to lean on our shoulders, and to hobble along by our side, under the monkish trammels of priests and kings, as she can. What a Colossus shall we be when the Southern continent comes up to our mark! What a stand will it secure as a ralliance for the reason & freedom of the globe! I like the dreams of the future better than the history of the past. So good night. I will dream on, always fancying that Mrs Adams and yourself are by my side marking the progress and the obliquities of ages and countries.”

“I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it.”

“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.”

“When governments fear the people, there is liberty. When the people fear the government, there is tyranny.”

“The boisterous sea of liberty is never without a wave. ”

“New York, like London, seems to be a cloacina [toilet] of all the depravities of human nature.”

“While the art of printing is left to us science can never be retrograde; what is once acquired of real knowledge can never be lost.”

“The main objects of all science, the freedom and happiness of man. . . . [are] the sole objects of all legitimate government.

“Pride costs us more than hunger, thirst, and cold.”

“An honest man can feel no pleasure in the exercise of power over his fellow citizens.”

“I [am] obliged to recur ultimately to my habitual anodyne, "I feel: therefore I exist." I feel bodies which are not myself: there are other existencies then. I call them "matter". I feel them changing place. This gives me "motion". Where there is an absence of matter, I call it "void", or "nothing", or "immaterial space". On the basis of sensation, of matter and motion, we may erect the fabric of all the certainties we can have or need.” 

“I am mortified to be told that, in the United States of America, the sale of a book can become a subject of inquiry, and of criminal inquiry too. ”