The astral plane, also called the astral world, is a plane whose existence was first postulated by classical, medieval, oriental and esoteric philosophies and mystery religions. It is the world of the celestial spheres, crossed by the soul in its astral body on the way to being born and after death, and generally said to be populated by angels, spirits or other immaterial beings. In the late 19th and early 20th century the term was popularized by Theosophy and neo-Rosicrucianism.
Plato and Aristotle taught that the stars were composed of a type of matter different from the four earthly elements – a fifth, ethereal element or quintessence that they referred to as the aethyr. In the “astral mysticism” of the classical world, the human psyche was composed of the same material, thus accounting for the influence of the stars upon human affairs.
Such doctrines were commonplace in mystery-schools and Hermetic and gnostic sects throughout the Roman Empire and influenced the early Christian church. Among Muslims, the “astral” world-view was soon rendered orthodox by Quranic references to the Prophet’s ascent through the seven heavens. Scholars took up the Greek Neoplatonist accounts as well as similar material in Hindu and Zoroastrian texts. By the 14th century, Dante was describing his own journey through the astral spheres of Paradise.
According to occult teachings the astral plane can be visited consciously through astral projection, meditation and mantra, near death experience, lucid dreaming, or other means. Individuals that are trained in the use of the astral vehicle can separate their consciousness in the astral vehicle from the physical body at will. Although human dreamers regularly visit the harmless lower astral planes, only trained wizards are able to visit the higher astral planes, which are inhabited by powerful and occasionally dangerous entities.