“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”

“The main objects of all science, the freedom and happiness of man. . . . [are] the sole objects of all legitimate government.

“I find that the harder I work, the more luck I seem to have.”

“It is while we are young that the habit of industry is formed. If not then, it never is afterward.”

“A coward is much more exposed to quarrels than a man of spirit.”

“We have no right to prejudice another in his civil enjoyments because he is of another church.”

“Let us save what remains: not by vaults and locks which fence them from the public eye and use in consigning them to the waste of time, but by such a multiplication of copies, as shall place them beyond the reach of accident.”

“I am convinced our own happiness requires that we should continue to mix with the world, and to keep pace with it as it goes. "

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

“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]” 

“The policy of the American government is to leave its citizens free, neither restraining them nor aiding them in their pursuits.”

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

“The art of life is the art of avoiding pain.”

“The object most interesting to me for the residue of my life, will be to see you both developing daily those principles of virtue and goodness which will make you valuable to others and happy in yourselves, and acquiring those talents and that degree of science which will guard you at all times against ennui, the most dangerous poison of life. A mind always employed is always happy. This is the true secret, the grand recipe for felicity....In a world which furnishes so many employments which are useful, and so many which are amusing, it is our own fault if we ever know what ennui is...”