Lucifer

Lucifer — from the Latin lūcifer, 'light-bringer' — was originally the Latin name for the morning star, the planet Venus at its dawn appearance. It occurs in the Latin Vulgate translation of Isaiah 14:12, where the prophet mocks the fallen king of Babylon: 'How art thou fallen from heaven, O Lucifer, son of the morning!' Christian tradition, following commentators from Origen and Jerome onward, read this passage as a veiled account of the fall of a chief angel from heaven — and the proper name Lucifer thus attached itself to the personification of that fall, later widely (though not universally) identified with Satan.

The distinct mythological figure of Lucifer — as opposed to Satan — was substantially elaborated in Christian literary and esoteric traditions. Dante's Inferno places Lucifer at the frozen centre of Hell as a three-faced titan; John Milton's Paradise Lost (1667) gave him the ambiguous grandeur that has coloured every subsequent Western portrayal — proud, brilliant, tragic, and articulate. In Romantic-era readings (William Blake, Percy Bysshe Shelley) Lucifer became a figure of rebellious enlightenment: the light-bringer who chose knowledge and autonomy over obedience.

Esoteric and theosophical traditions have preserved a distinction between Satan and Lucifer that mainstream Christianity generally collapsed. In this reading Lucifer is not the personification of evil but the archetypal Illuminator — the one who brings the light of self-conscious awareness, at the cost of exile from the unconscious paradisal state. Rudolf Steiner's anthroposophy elaborated a specifically Luciferian principle (pride, intellectual pride, unearned transcendence) as one of two opposing spiritual forces (with Ahriman, materialism, as the other) between which the human being must find balance.

In visionary and psychedelic reports, encounters described as Luciferian rather than Satanic recur with a specific phenomenological signature: an unearthly beauty accompanied by intense pride and isolation; a bright, disdainful intelligence; the felt presence of a being who chose separation over union and knows the cost. The distinction between Satan (adversary, accuser, shadow) and Lucifer (fallen light, exiled autonomy, illuminated pride) is one the mystical literature has always maintained more carefully than popular usage.

Sources:
Wikipedia — Lucifer
Wikipedia — Fallen angel