An amalgamation of two books published in 1841 and 1844, the 21 pieces known as "Essays: First and Second Series" describe Emerson's concepts of self-reliance, the law of compensation (a sort of yin-yang polarity in morality), and the transcendental Over-Soul, an ideal Emerson first enunciated (without naming it as such) in his infamous Divinity School Address, for which he was accused of atheism. "The world is not the product of manifold power, but of one will, of one mind; and that one mind is everywhere active," he said to Harvard's startled divinity students and teachers. "All things proceed out of the same spirit." In these essays, he expands upon this notion of the individual Self as part of a universal All, of the human soul bound by a physical body yet tethered to an omniscient spirit.
Emerson's metaphysics alternates among a quasi-pantheistic belief in the unity of humanity, nature, and God; a monistic view that All is One; a mystical channeling of universal truths; and an anthropocentric faith in the primacy of human experience. Through reflection and meditation, humans can experience God. "Ineffable is the union of man and God in every act of the soul," he writes in the essay titled "The Over-Soul." "The simplest person who in his integrity worships God, becomes God."
The form of Emerson's "essays" displays his training as a preacher, and his lectures served as rough drafts; but, although they read like sermons, they are more like prose poems, heavily indebted to Plutarch, Plotinus, and Montaigne. In addition to "Self-Reliance" and "The Over-Soul," the most important of these essays are probably "History," "Compensation," and "The Poet." Anecdotes, evidence, and "scientific" observation play a minor role in his writing, and transitional devices are sparse; his essays are built instead of argument by aphorism, chains of clever and commonsensical quips, and contemplative reflection in a nearly conversational style. (A friend of mine once joked, perceptively, that the Quotable Emerson would be pretty much the same as the unabridged version of the book you have here.)
Emerson's idealism and romanticism can seem hopelessly abstract--a failing that carried over into his personal relations. (Responding to his discussion on "Friendship," Caroline Sturgis wrote to him, "With all your faith in Man, you have but little faith in men.") The ambiguities of his writing and their myriad interpretations have provided the foundations for disparate schools of thought. On the one hand, his philosophic arguments and literary characteristics anticipate Walt Whitman's ode to the self, Nietzsche's "ubermensch," Williams James's "stream-of-consciousness," Dewey's instrumentalism, and Jung's concept of the universal unconscious or racial memory. On the other hand, there is a direct descent from the sermonizing, inspirational quality of Emerson's works to various strands of New Thought spiritualism, the motivational guides of Norman Vincent Peale and Dale Carnegie, and the ongoing popularity of books by self-help gurus. (Indeed, one could argue that Emerson's books established the genre in America.)
It is impossible, then, to overstate Emerson's influence on subsequent literature and thought, both highbrow and mass-market. Many (perhaps most) of today's readers might be turned off by the abstract Neo-Platonism of Emerson's work, and his seemingly endless stream of metaphors and maxims can be, at times, somnambulistic. (I personally find his philosophy completely alien to my own worldview.) But even so, Emerson should be read in order to understand both the phenomenon of New England transcendentalism, which may well be the only uniquely American philosophy of the nineteenth century, and the rise of individualism, which donned a uniquely American character during the twentieth.