Boston's Unitarians had given up the Trinity, and they rested what remained of Christianity on evidence. Andrews Norton, a Harvard scholar of the Bible, held that the miracles reported in the gospels proved the religion true. Ralph Waldo Emerson grew up inside this faith: his father was minister of Boston's First Church, and in March 1829 Emerson himself was ordained junior pastor of the Second Church. The claim he spent the rest of his life making left that evidence with nothing to do. Every person, he held, can know what is true and right directly, by trusting what they see for themselves, and needs no miracle, scripture or church to vouch for it.
The break with his own profession came first. His first wife, Ellen Tucker, died of tuberculosis in February 1831, and in June 1832 he wrote in his journal that the ministry was an antiquated profession. In September he told his congregation that he could no longer administer the Lord's Supper, the bread and wine of communion, and resigned.
The lecture hall took the place of the pulpit. On 5 November 1833 he gave "The Uses of Natural History," the first of some 1,500 lectures; by the 1850s he was giving as many as eighty a year, as far west as St. Louis. His first book, Nature, went on sale in September 1836, paid for by himself and printed without his name. It argued that the natural world is a language in which every fact stands for a spiritual one, so that a person who reads it attentively has no need of a church in between.
Harvard heard the argument twice. In "The American Scholar," given to the Phi Beta Kappa Society on 31 August 1837, he told students to learn from nature and from their own action before they learned from European books. On 15 July 1838, invited by the graduating class of the Divinity School, he told the future ministers that the church had turned Jesus into a worker of past miracles and that each of them should preach out of a first-hand experience of God. Norton attacked the new thinking in print as a modern form of unbelief. Emerson made no reply, and Harvard did not invite him to speak again for nearly thirty years.
"Self-Reliance," in the Essays of 1841, gives the claim the form most often quoted. What a person sees to be true in private, if they trust it fully, turns out to be true for everyone, and the pressure to conform — to a church, a party, even to one's own earlier statements — keeps most people from knowing what they know. "The Over-Soul," in the same book, supplies the reason: every person shares in a single mind. In January 1842 his five-year-old son Waldo died of scarlet fever. "Experience," the essay he wrote out of that loss, admits that grief taught him nothing and describes life as a run of moods with no standpoint outside them; set beside Nature, it reads as a revision.
He came late to politics: only from 1844 did he speak regularly against slavery. In May 1851 he told a Concord audience that the new Fugitive Slave Act, which required officials and citizens of the free states to help return people who had escaped slavery, was a law every one of them should break. The Conduct of Life of 1860 opens with "Fate." Some of its passages treat whole peoples as fixed by their physical makeup, and modern readers single them out as disturbing. In 1870 Harvard invited him back to give a course of lectures on philosophy; by the time he repeated it in 1871, his memory had begun to fail.
Friedrich Nietzsche read the essays in German translation and copied passages from "History" and "Self-Reliance" into his journals. Emerson's ideas about change and about the ideal in the commonplace run through the pragmatism of William James, his godson, and of John Dewey. A century after his death the philosopher Stanley Cavell made him a primary source for what Cavell called moral perfectionism: the view that a self is never finished and is always on the way to a better self that it has not yet reached but can reach.