“The executive power in our government is not the only, perhaps not even the principal, object of my solicitude. The tyranny of the legislature is really the danger most to be feared, and will continue to be so for many years to come. The tyranny of the executive power will come in its turn, but at a more distant period.” 

“The whole art of government consists in the art of being honest. Only aim to do your duty, and mankind will give you credit where you fail.”

“The bill for establishing religious freedom, the principles of which had, to a certain degree, been enacted before, I had drawn in all the latitude of reason & right. It still met with opposition; but, with some mutilations in the preamble, it was finally passed; and a singular proposition proved that it's protection of opinion was meant to be universal. Where the preamble declares that coercion is a departure from the plan of the holy author of our religion, an amendment was proposed, by inserting the word "Jesus Christ," so that it should read "a departure from the plan of Jesus Christ, the holy author of our religion." The insertion was rejected by a great majority, in proof that they meant to comprehend, within the mantle of it's protection, the Jew and the Gentile, the Christian and Mahometan, the Hindoo, and infidel of every denomination.”

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

“...never [enter] into dispute or argument with another. I never saw an instance of one of two disputants convincing the other by argument. I have seen many, on their getting warm, becoming rude, & shooting one another. ... When I hear another express an opinion which is not mine, I say to myself, he has a right to his opinion, as I to mine; why should I question it? His error does me no injury, and shall I become a Don Quixote, to bring all men by force of argument to one opinion? ... There are two classes of disputants most frequently to be met with among us. The first is of young students, just entered the threshold of science, with a first view of its outlines, not yet filled up with the details & modifications which a further progress would bring to their knoledge. The other consists of the ill-tempered & rude men in society, who have taken up a passion for politics. ... Consider yourself, when with them, as among the patients of Bedlam, needing medical more than moral counsel. Be a listener only, keep within yourself, and endeavor to establish with yourself the habit of silence, especially on politics. In the fevered state of our country, no good can ever result from any attempt to set one of these fiery zealots to rights, either in fact or principle. They are determined as to the facts they will believe, and the opinions on which they will act. Get by them, therefore, as you would by an angry bull; it is not for a man of sense to dispute the road with such an animal.”

“On every question of construction (of the Constitution) let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit of the debates, and instead of trying what meaning may be squeezed out of the text, or invented against it, conform to the probable one in which it was passed.”

“Tyranny is defined as that which is legal for the government but illegal for the citizenry.”

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

“The inquisition of public opinion overwhelms in practice the freedom asserted by the laws in theory.”

“Without books, I would certainly die.”

“The glow of one warm thought is to me worth more than money”

“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]” 

“[Christianity is] the most ... perverted system that ever shone on man.”

“… 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 and errors.”

“The happiest moments of my life have been the few which I have passed at home in the bosom of my family.”