“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...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.”

“I am satisfied, and sufficiently occupied with the things which are, without tormenting or troubling myself about those which may indeed be, but of which I have no evidence.”

“To your request of my opinion of the manner in which a newspaper should be conducted, so as to be most useful, I should answer, ‘by restraining it to true facts & sound principles only.’ Yet I fear such a paper would find few subscribers. It is a melancholy truth, that a suppression of the press could not more compleatly deprive the nation of its benefits, than is done by its abandoned prostitution to falsehood. Nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle. The real extent of this state of misinformation is known only to those who are in situations to confront facts within their knolege with the lies of the day. I really look with commiseration over the great body of my fellow citizens, who, reading newspapers, live & die in the belief, that they have known something of what has been passing in the world in their time; whereas the accounts they have read in newspapers are just as true a history of any other period of the world as of the present, except that the real names of the day are affixed to their fables. General facts may indeed be collected from them, such as that Europe is now at war, that Bonaparte has been a successful warrior, that he has subjected a great portion of Europe to his will, &c., &c.; but no details can be relied on. I will add, that the man who never looks into a newspaper is better informed than he who reads them; inasmuch as he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. He who reads nothing will still learn the great facts, and the details are all false.” —Letter to John Norvell, 14 June 1807 [Works 10:417--18]” 

“Enlighten the people, and tyranny and oppressions of body and mind will vanish like evil spirits at the dawn of day.”

“It be urged that the wild and uncultivated tree, hitherto yielding sour and bitter fruit only, can never be made to yield better; yet we know that the grafting art implants a new tree on the savage stock, producing what is most estimable in kind and degree. Education, in like manner, engrafts a new man on the native stock, and improves what in his nature was vicious and perverse into qualities of virtue and social worth.”

“Every citizen should be a soldier. This was the case with the Greeks and Romans, and must be that of every free state.”

“The laws that forbid the carrying of arms... disarm only those who are neither inclined nor determined to commit crimes.”

“I may grow rich by an art I am compelled to follow; I may recover health by medicines I am compelled to take against my own judgment; but I cannot be saved by a worship I disbelieve and abhor.”

“The legitimate powers of government extend to such acts only as are injurious to others. It does me no injury for my neighbor to say there are twenty gods or no god. It neither picks my pocket nor breaks my leg.”

“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.”

“An injured friend is the bitterest of foes.”

“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.” 

“To the corruptions of christianity I am indeed opposed; but not to the genuine precepts of Jesus himself. I am a Christian in the only sense in which he wished any one to be; sincerely attached to his doctrines, in preference to all others; ascribing to himself every human excellence, and believing he never claimed any other.”

“They (religions) dread the advance of science as witches do the approach of daylight and scowl on the fatal harbinger announcing the subversions of the duperies on which they live.”

“The whole art of government consists in the art of being honest.”