Who wrote the most famous part of the Declaration?

Thomas Jefferson wrote the most famous part of the Declaration of Independence, the second paragraph that opens "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness." That single sentence has become the most quoted line in American political writing and has shaped political movements around the world for two and a half centuries.

Jefferson drafted the Declaration between roughly June 11 and June 28, 1776 in his rented rooms on the second floor at the corner of Seventh and Market Streets in Philadelphia. He worked on a small folding desk, now preserved at the Smithsonian, that he had designed himself. He was 33 years old, the second youngest member of the Committee of Five appointed by the Second Continental Congress, and was selected to do the writing because of his recognized literary skill (his 1774 pamphlet A Summary View of the Rights of British America had circulated widely) and because Virginia's leadership of the independence movement made it diplomatically appropriate.

Jefferson drew on three main sources for the famous opening. John Locke's Second Treatise of Civil Government, published anonymously in 1689, provided the theory that humans in a state of nature possess natural rights and form government to secure them. George Mason's Virginia Declaration of Rights, drafted on June 12, 1776 and adopted by the Virginia Convention, provided the immediate template; Mason's text declared that all men are by nature equally free and independent and have inherent rights including the enjoyment of life and liberty, with the means of acquiring and possessing property, and pursuing and obtaining happiness and safety. Jefferson's own 1776 draft preamble for the Virginia Constitution provided structural ideas.

Benjamin Franklin made one of the most famous edits, changing Jefferson's "we hold these truths to be sacred and undeniable" to "we hold these truths to be self-evident," a small change that strengthened the philosophical claim. John Adams and Franklin made about 47 edits in committee. Congress edited the draft on July 2, 3, and 4, 1776, removing roughly a quarter of the original, including a long passage attacking King George III for the Atlantic slave trade that Georgia and South Carolina insisted be deleted. Jefferson resented the changes but accepted them.

The final document was adopted on July 4, 1776 with the famous paragraph essentially as Jefferson had drafted it. Decades later, in 1825, Jefferson described the Declaration as an expression of the American mind drawing on common sense, harmonized with the prevailing sentiments of the day and not invented by him.