“[Christianity is] the most ... perverted system that ever shone on man.”

“There exists indeed an opposition to it [building of UVA, Jefferson's secular college] by the friends of William and Mary, which is not strong. The most restive is that of the priests of the different religious sects, who dread the advance of science as witches do the approach of day-light; and scowl on it the fatal harbinger announcing the subversion of the duperies on which they live. In this the Presbyterian clergy take the lead. The tocsin is sounded in all their pulpits, and the first alarm denounced is against the particular creed of Doctr. Cooper; and as impudently denounced as if they really knew what it is.

“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”

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

“He who knows best knows how little he knows.”

“To take from one because it is thought that his own industry and that of his father’s has acquired too much, in order to spare to others, who, or whose fathers have not exercised equal industry and skill, is to violate arbitrarily the first principle of association--the guarantee to every one of a free exercise of his industry and the fruits acquired by it.”

“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. I knew that age well; I belonged to it, and labored with it. It deserved well of its country. It was very like the present, but without the experience of the present; and forty years of experience in government is worth a century of book-reading; and this they would say themselves, were they to rise from the dead. I am certainly not an advocate for frequent and untried changes in laws and constitutions. I think moderate imperfections had better be borne with; because, when once known, we accommodate ourselves to them, and find practical means of correcting their ill effects. 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. We might as well require a man to wear still the coat which fitted him when a boy, as civilized society to remain ever under the regimen of their barbarous ancestors.” 

“A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise and independence to the mind. Games played with the ball and others of that nature are too violent for the body and stamp no character on the mind. Let your gun therefore be your constant companion of your walks.”

“I steer my bark with Hope in the head, leaving Fear astern. My hopes, indeed, sometimes fail; but not oftener than the forebodings of the gloomy.”

“I believe that every human mind feels pleasure in doing good to another.”

“Can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of people that these liberties are the gift of God?” 

“Perceiving the order of nature to be that individual happiness shall be inseparable from the practice of virtue, I am willing to hope it may have ordained that the fall of the wicked shall be the rise of the good.  To J. Correa de Serra, Monticello, Apr. 19, 1814”

“The art of life is the art of avoiding pain; and he is the best pilot, who steers clearest of the rocks and shoals with which it is beset.”

“I have received the favor of your letter of August 17th, and with it the volume you were so kind as to send me on the Literature of Negroes. Be assured that no person living wishes more sincerely than I do, to see a complete refutation of the doubts I have myself entertained and expressed on the grade of understanding allotted to them by nature, and to find that in this respect they are on a par with ourselves. My doubts were the result of personal observation on the limited sphere of my own State, where the opportunities for the development of their genius were not favorable, and those of exercising it still less so. I expressed them therefore with great hesitation; but whatever be their degree of talent it is no measure of their rights. Because Sir Isaac Newton was superior to others in understanding, he was not therefore lord of the person or property of others. On this subject they are gaining daily in the opinions of nations, and hopeful advances are making towards their reestablishment on an equal footing with the other colors of the human family.”

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