“Neither Pagan nor Mahamedan nor Jew ought to be excluded from the civil rights of the Commonwealth because of his religion. -quoting John Locke's argument.”

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

“All eyes are opened, or opening, to the rights of man. The general spread of the light of science has already laid open to every view the palpable truth that the mass of mankind has not been born with saddles on their backs, nor a favored few booted and spurred, ready to ride them legitimately, by the grace of God. These are grounds of hope for others. For ourselves, let the annual return of this day forever refresh our recollection of these rights, and an undiminished devotion to them.”

“...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.”

“The truth is that the greatest enemies to the doctrines of Jesus are those calling themselves the expositors of them, who have perverted them for the structure of a system of fancy absolutely incomprehensible, and without any foundation in his genuine words. And the day will come when the mystical generation of Jesus by the supreme being as his father in the womb of a virgin will be classed with the fable of the generation of Minerva in the brain of Jupiter, but we may hope that the dawn of reason and freedom of thought in these United States will do away with all this artificial scaffolding and restore to us the primitive and genuine doctrines of this, the most venerated reformer of human errors. -Thomas Jefferson to John Adams (April 11, 1823)” 

“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.” 

“If Americans desire to be both ignorant and free, they want what never has been and what never will be.”

“When describing the University of Virginia: Here, We are not afraid to follow truth wherever it may lead, nor to tolerate any error so long as reason is left free to combat it.”

“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.”

“Leave no authority existing not responsible to the people.”

“History, I believe, furnishes no example of a priest-ridden people maintaining a free civil government. This marks the lowest grade of ignorance of which their civil as well as religious leaders will always avail themselves for their own purposes.”

“Whenever you do a thing, act as if all the world were watching.”

“Everything is useful which contributes to fix in the principles and practices of virtue.”

“As Thomas Jefferson proclaimed, “In matters of fashion, swim with the current. In matters of conscience, stand like a rock.”

“May it [American independence] be to the world, what I believe it will be, (to some parts sooner, to others later, but finally to all,) the signal of arousing men to burst the chains under which monkish ignorance and superstition had persuaded them to bind themselves, and to assume the blessings and security of self-government. That form which we have substituted, restores the free right to the unbounded exercise of reason and freedom of opinion. All eyes are opened, or opening, to the rights of man. The general spread of the light of science has already laid open to every view the palpable truth, that the mass of mankind has not been born with saddles on their backs, nor a favored few booted and spurred, ready to ride them legitimately... These are grounds of hope for others. For ourselves, let the annual return of this day forever refresh our recollections of these rights, and an undiminished devotion to them.