“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.{Letter to John Adams, from Monticello, 15 August 1820}”

“I [am] obliged to recur ultimately to my habitual anodyne, "I feel: therefore I exist." I feel bodies which are not myself: there are other existencies then. I call them "matter". I feel them changing place. This gives me "motion". Where there is an absence of matter, I call it "void", or "nothing", or "immaterial space". On the basis of sensation, of matter and motion, we may erect the fabric of all the certainties we can have or need.”

“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.[Letter to José Francesco Corrê a Da Serra - Monticello, April 11, 1820]”

“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 all this artificial scaffolding...{Letter to John Adams, April 11, 1823}”

“I am savage enough to prefer the woods, the wilds, and the independence of Monticello, to all the brilliant pleasures of this gay capital [Paris].”

“...it is not to be understood that I am with him [Jesus] in all his doctrines. I am a Materialist, he takes the side of spiritualism; he preaches the efficacy of repentance toward forgiveness of sin. I require a counterpoise of good works to redeem it... Among the sayings & discourses imputed to him by his biographers, I find many passages of fine imagination, correct morality, and of the most lovely benevolence: and others again of so much ignorance, so much absurdity, so much untruth, charlatanism, and imposture, as to pronounce it impossible that such contradictions should have proceeded from the same being.[Letter to William Short, 13 April 1820]”

“If the present Congress errs in too much talking, how can it be otherwise in a body to which the people send 150 lawyers, whose trade it is to question everything, yield nothing, & talk by the hour? That 150 lawyers should do business together ought not to be expected.”