|1483 copy of De rerum natura|
In a letter to William Short (October 31, 1819), Jefferson proclaims that he is an Epicurean. He writes: “I too am an Epicurean. I consider the genuine (not the imputed) doctrines of Epicurus as containing everything rational in moral philosophy which Greece and Rome have left us.”
In a letter to Charles Thomson (January 9, 1816), Jefferson says that Epicureanism is the most rational philosophical system of the ancients “notwithstanding the calumnies of the Stoics and caricatures of Cicero.” He says that Epicureanism is “as frugal of vicious indulgence, and fruitful of virtue as the hyperbolical extravagances of his rival sects.”
In a letter to his nephew Peter Carr (August 10, 1787), Jefferson gives an account of his Epicurean philosophy. Here’s an excerpt: “He who made us would have been a pitiful bungler if he had made the rules of our moral conduct a matter of science. For one man of science, there are thousands who are not. What would have become of them? Man was destined for society. His morality, therefore, was to be formed to this object. He was endowed with a sense of right and wrong, merely relative to this. This sense is as much a part of his Nature, as the sense of hearing, seeing, feeling; it is the true foundation of morality, and not the [beautiful], truth, &c., as fanciful writers have imagined. The moral sense, or conscience, is as much a part of man as his leg or arm. It is given to all human beings in a stronger or weaker degree, as force of members is given them in a greater or less degree. It may be strengthened by exercise, as may any particular limb of the body. This sense is submitted, indeed, in some degree, to the guidance of reason; but it is a small stock which is required for this: even a less one than what we call common sense. State a moral case to a plowman and a professor. The former will decide it as well, & often better than the latter, because he has not been led astray by artificial rules.”
In Nature’s God: The Heretical Origins of the American Republic, Matthew Stewart says that Jefferson, at times, walked around with Lucretius’s poem De rerum natura (which is written with the goal of explaining Epicurean philosophy) in his pocket. In 1815, the library that Jefferson turned over to Congress included eight editions of De rerum natura. Jefferson collected translations of the poem in English, French and Italian. Jefferson also owned Pierre Gassendi’s three volume set on the philosophy of Epicurus.
The principle of “pursuit of happiness,” which Jefferson included in the Declaration of Independence is inspired by Epicurean thought.