“The fantastical idea of virtue and the public good being a sufficient security to the state against the commission of crimes...was never mine. It is only the sanguinary hue of our penal laws which I meant to object to. Punishments I know are necessary, and I would provide them strict and inflexible, but proportioned to the crime. Death might be inflicted for murder and perhaps for treason, [but I] would take out of the description of treason all crimes which are not such in their nature. Rape, buggery, etc., punish by castration. All other crimes by working on high roads, rivers, gallies, etc., a certain time proportioned to the offence... Laws thus proportionate and mild should never be dispensed with. Let mercy be the character of the lawgiver, but let the judge be a mere machine. The mercies of the law will be dispensed equally and impartially to every description of men; those of the judge or of the executive power will be the eccentric impulses of whimsical, capricious designing man.”

“...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 whole commerce between master and slave is a perpetual exercise of the most boisterous passions, the most unremitting despotism on the one part, and degrading subjugation on the other. Our children see this, and learn to imitate it: for man is an imitative animal.”

“The opinions of men are not the object of civil government, nor under its jurisdiction.” 

“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...But I know also, that laws and institutions must go hand in hand with the progress of the human mind. As that becomes more developed, more enlightened, as new discoveries are made, new truths disclosed, and manners and opinions change with the change of circumstances, institutions must advance also, and keep pace with the times.”

“The man who reads nothing at all is better educated than the man who reads nothing but newspapers.”

“You are now old enough to know how very important to your future life will be the manner in which you employ your present time”

“This institution will be based on the illimitable freedom of the human mind. For 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.”

“War is an instrument entirely inefficient toward redressing wrong; and multiplies, instead of indemnifying losses.”

“No occupation is so delightful to me as the culture of the earth, no culture comparable to that of the garden...But though an old man, I am but a young gardener.”

“And to preserve their independence, we must not let our rulers load us with perpetual debt. We must make our election between economy and liberty, or profusion and servitude. If we run into such debts, as that we must be taxed in our meat and in our drink, in our necessaries and our comforts, in our labors and our amusements, for our callings and our creeds, as the people of England are, our people, like them, must come to labor sixteen hours in the twenty-four, give the earnings of fifteen of these to the government for their debts and daily expenses; and the sixteenth being insufficient to afford us bread, we must live, as they now do, on oatmeal and potatoes; have no time to think, no means of calling the mismanagers to account; but be glad to obtain subsistence by hiring ourselves to rivet their chains on the necks of our fellow-sufferers.” 

“Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blind-folded fear.”

“It is error alone which needs the support of government. Truth can stand by itself.”

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

“With your talents and industry, with science, and that steadfast honesty, which eternally pursues right, regardless of consequences, you may promise yourself everything but health, without which there is no happiness.”