“Our greatest happiness does not depend on the condition of life in which chance has placed us, but is always the result of a good conscience, good health, occupation, and freedom in all just pursuits.”

“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.” 

“And for the support of this declaration, with a firm reliance on the protection of divine providence, we mutually pledge to each other our lives, our fortunes and our sacred honor.”

“...as we advance in life these things fall off one by one , and I suspect we are left with only Homer and Virgil, perhaps with only Homer alone.”

“If you want something you’ve never had, you’ve got to do something you’ve never done before.”

“I am a sect by myself, as far as I know.”

“I never will, by any word or act, bow to the shrine of intolerance or admit a right of inquiry into the religious opinions of others.”

“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]” 

“Leave all the afternoon for exercise and recreation, which are as necessary as reading. I will rather say more necessary because health is worth more than learning.”

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

“Determine never to be idle. No person will have occasion to complain of the want of time, who never loses any. It is wonderful how much may be done, if we are always doing.”

“Men have differed in opinion, and been divided into parties by these opinions, from the first origin of societies; and in all governments where they have been permitted freely to think and to speak. the same political parties which now agitate the U.S. have existed through all time. Whether the power of the people, or that of the (best men; nobles) should prevail, were questions which kept the states of Greece and rome in eternal convulsions...” 

“If you want something you've never had You must be willing to do something you've never done.” 

“He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me.” 

“It is more dangerous that even a guilty person should be punished without the forms of law than that he should escape.”