“...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 pretense that the workings of the mind, like the actions of the body, are subject to the control of laws, does not seem sufficiently demolished. ... The legitimate powers of government extend to such acts only as are injurious to others.”

“There is a ripeness of time for death,  regarding others as well as ourselves, when it is reasonable we should drop off, and make room for  another growth. When we have lived our generation out, we should not wish to encroach on another.”

“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...”

“The natural progress of things is for liberty to yield, and government to gain ground.”

“When once we quit the basis of sensation, all is in the wind. To talk of immaterial existences is to talk of nothings. To say that the human soul, angels, god, are immaterial, is to say they are nothings, or that there is no god, no angels, no soul. I cannot reason otherwise: but I believe I am supported in my creed of materialism by Locke, Tracy, and Stewart.

“And can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of the people that these liberties are the gift of God? That they are not to be violated but with His wrath? Indeed, I tremble for my country when I reflect that God is just; that his justice cannot sleep forever.”

“In every country and in every age, the priest has been hostile to liberty. He is always in alliance with the despot, abetting his abuses in return for protection to his own.”

“I wish that all nations may recover and retain their independence; that those which are overgrown may not advance beyond safe measures of power, that a salutary balance may be ever maintained among nations, and that our peace, commerce, and friendship, may be sought and cultivated by all. It is our business to manufacture for ourselves whatever we can, to keep our markets open for what we can spare or want; and the less we have to do with the amities or enmities of Europe, the better. Not in our day, but at no distant one, we may shake a rod over the heads of all, which may make the stoutest of them tremble. But I hope our wisdom will grow with our power, and teach us, that the less we use our power, the greater it will be.”

“Speaking one day to Monsieur de Buffon, on the present ardor of chemical inquiry, he affected to consider chemistry but as cookery, and to place the toils of the laboratory on the footing with those of the kitchen. I think it, on the contrary, among the most useful of sciences, and big with future discoveries for the utility and safety of the human race.”