“If by religion we are to understand sectarian dogmas, in which no two of them agree, then your exclamation on that hypothesis is just, "that this would be the best of worlds if there were no religion in it.” 

“Reason and free inquiry are the only effectual agents against error.”

“He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our People, and eat out their substance.”

“You seem to consider the judges as the ultimate arbiters of all constitutional questions; a very dangerous doctrine indeed, and one which would place us under the despotism of an oligarchy. Our judges are as honest as other men, and not more so. They have, with others, the same passions for party, for power, and the privilege of their corps.... Their power [is] the more dangerous as they are in office for life, and not responsible, as the other functionaries are, to the elective control. The Constitution has erected no such single tribunal, knowing that to whatever hands confided, with the corruptions of time and party, its members would become despots. It has more wisely made all the departments co-equal and co-sovereign within themselves.” 

“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]” 

“I like the dreams of the future better than the history of the past.”

“All that is necessary for a student is access to a library.”

“The hocus-pocus phantasm of a God like another Cerberus, with one body and three heads, had its birth and growth in the blood of thousands and thousands of martyrs... In fact, the Athanasian paradox that one is three, and three but one, is so incomprehensible to the human mind, that no candid man can say he has any idea of it, and how can he believe what presents no idea? He who thinks he does, only deceives himself. He proves, also, that man, once surrendering his reason, has no remaining guard against absurdities the most monstrous, and like a ship without a rudder, is the sport of every wind. With such persons, gullibility which they call faith, takes the helm from the hand of reason, and the mind becomes a wreck.

“I am certainly not an advocate for frequent and untried changes in laws and constitutions...but I know also that laws and constitutions must go hand in hand with the progress of the human mind.....”

“Whereas it appeareth that however certain forms of government are better calculated than others to protect individuals in the free exercise of their natural rights, and are at the same time themselves better guarded against degeneracy, yet experience hath shewn, that even under the best forms, those entrusted with power have, in time, and by slow operations, perverted it into tyranny; and it is believed that the most effectual means of preventing this would be, to illuminate, as far as practicable, the minds of the people at large, ....whence it becomes expedient for promoting the publick happiness that those persons, whom nature hath endowed with genius and virtue, should be rendered by liberal education worthy to receive, and able to guard the sacred deposit of the rights and liberties of their fellow citizens, and that they should be called to that charge without regard to wealth, birth or accidental condition of circumstance.”

“I agree with yours of the 22d that a professorship of Theology should have no place in our institution. but we cannot always do what is absolutely best. those with whom we act, entertaining different views, have the power and the right of carrying them into practice. truth advances, & error recedes step by step only; and to do to our fellow-men the most good in our power, we must lead where we can, follow where we cannot, and still go with them, watching always the favorable moment for helping them to another step.

“[n regard to Jesus believing himself inspired] This belief carried no more personal imputation than the belief of Socrates that he was under the care and admonition of a guardian demon. And how many of our wisest men still believe in the reality of these inspirations while perfectly sane on all other subjects (Works, Vol. iv, p. 327).”

“Can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of people that these liberties are the gift of God?” 

“I hope that we shall crush in its birth the aristocracy of our monied corporations which dare already to challenge our government to a trial of strength, and bid defiance to the laws of our country.”

“The most valuable of all talents is that of never using two words when one will do.”