“In matters of principal stand like a rock.”

“He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors.”

“The Tree of Liberty must be refreshed from time to time with the blood of patriots and tyrant. It is its natural manure.”

“all experience hath shewn, that mankind are more disposed to suffer, while evils are sufferable, than to right themselves by abolishing the forms to which they are accustomed.”

“In every country and every age, the priest had been hostile to Liberty.”

“when you come to the end of your rope, tie a knot and hang on”

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

“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 sincerely believe the banking institutions having the issuing power of money, are more dangerous to liberty than standing armies.”

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

“...We are all Federalists,and we are all Republicans.”

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

“Nothing gives one person so much advantage over another as to remain always cool and unruffled under all circumstances.”

“Whenever any form of government becomes destructive of these ends [life, liberty, and the pursuit of happiness] it is the right of the people to alter or abolish it, and to institute new government...” 

“I consider him [Alexander von Humboldt] the most important scientist whom I have met.”