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

“the measure of society is how it treats the weakest members”

“Our civil rights have no dependence upon our religious opinions more than our opinions in physics or geometry.”

“Experience demands that man is the only animal which devours his own kind, for I can apply no milder term to the general prey of the rich on the poor.”

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

“History, by apprising [the people] of the past, will enable them to judge of the future.” 

“And can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of the people that these liberties are the gift of God? That they are not to be violated but with His wrath? Indeed, I tremble for my country when I reflect that God is just; that his justice cannot sleep forever.”

“...it is not to be understood that I am with him [Jesus] in all his doctrines. I am a Materialist, he takes the side of spiritualism; he preaches the efficacy of repentance toward forgiveness of sin. I require a counterpoise of good works to redeem it... Among the sayings & discourses imputed to him by his biographers, I find many passages of fine imagination, correct morality, and of the most lovely benevolence: and others again of so much ignorance, so much absurdity, so much untruth, charlatanism, and imposture, as to pronounce it impossible that such contradictions should have proceeded from the same being.

“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]” 

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

“War is an instrument entirely inefficient toward redressing wrong; and multiplies, instead of indemnifying losses.”

“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.”

“Was the government to prescribe us our medicine and diet, our bodies would be in such keeping as our souls are now."

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

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