Éliphas Lévi was born Alphonse Louis Constant on 8 February 1810 in Paris, the son of a shoemaker. He was educated at the expense of the Church — first at a parish school, then at the seminary of Saint-Sulpice, where he trained for the priesthood. He never took holy orders; a combination of his radical political views, his romantic entanglements and his heterodox theological opinions led to his departure from the seminary in the 1830s. He would spend the rest of his life in the ambiguous position of a man deeply formed by Catholic theology and ritual who had rejected the institution of the Church.
Throughout the 1840s Constant was active in radical socialist politics — writing pamphlets and a book called The Gospel of Liberty that landed him briefly in prison. He married Noémie Cadiot in 1846 (the marriage was turbulent and eventually failed). He was associated with various utopian and socialist thinkers of the period and was in many ways a man of the revolutionary left before his turn toward occultism.
The transformation came in the early 1850s. Constant — now writing under the Hebrew translation of his name, Éliphas Lévi — immersed himself in the study of Kabbalah, Hermeticism, Neoplatonism, ceremonial magic and the Tarot. In 1854 he visited London, where he performed a ritual evocation of the spirit of Apollonius of Tyana (which he described in remarkable detail but with characteristic ambiguity about what actually occurred). In 1855 he published Dogme et Rituel de la Haute Magie — the book that created modern Western occultism.
The remaining twenty years of his life were devoted to writing and to correspondence with an international network of students and admirers. He was widely regarded as the foremost occult authority in Europe. He died in Paris on 31 May 1875 — the same year, it is often noted, that Aleister Crowley was born. Crowley later claimed to be Lévi's reincarnation, a claim he made somewhat seriously.