The word 'occult' comes from the Latin occultus, meaning hidden, secret, covered up. It comes from the verb occultare, 'to hide' — the same root behind 'occlude' (to block, like a clogged artery) and 'occulted' (like a star hidden behind the moon for a moment). The word says nothing about good or evil. It just means hidden. When astronomers talk about a 'solar occultation,' they mean one object blocking another from view — not devil worship. The 'occult sciences' were simply the study of hidden causes: astrology, alchemy, magic, and the kind of natural study people did before modern science. This matters because the word has been used as a weapon for so long, by so many churches trying to crush it, that most people can not hear it without flinching at some idea of danger or madness. That fear is a leftover of old power struggles. It is not what the subject is about.
The Western occult tradition is a specific body of teaching and practice that has been passed down, often in secret, since at least the 3rd century CE. It has a few main roots. Hermeticism is the system linked to Hermes Trismegistus, which blends Egyptian and Greek thought and shows up most fully in the Corpus Hermeticum. Neo-Platonism is the late Greek philosophy of Plotinus, Porphyry, and Iamblichus, which gave magic its big-picture ideas. Kabbalah is the Jewish mystical tradition, especially the Sefer Yetzirah and the Zohar, whose map of the cosmos got taken up by Christian and later non-religious occultists from the Renaissance on. Alchemy is the work of turning base metal into gold — both literally in a lab and, more deeply, as a way to turn the lower self into the higher self. And astrology maps the patterns of the sky onto human life. All of these streams came together in Renaissance Florence, in the circle of Marsilio Ficino and Giovanni Pico della Mirandola, who built the first real synthesis of Hermeticism, Neo-Platonism, and Kabbalah — the seed of the Western occult tradition we know today.
The Western occult tradition was not hidden because the people practicing it were evil. It was hidden because their ideas scared the people in charge — mainly the medieval and early modern Christian Church, but also Islamic and Jewish authorities in their own regions. Hermeticism said the divine spark lives inside you and you can reach it directly with the right knowledge and practice. That cut out the Church, which claimed to be the only path to God's grace. Kabbalah said the letters and numbers of the Torah hold a hidden teaching that a trained mystic can read. That cut out the rabbis who claimed sole authority to interpret. Alchemy said people could study and transform the natural world themselves. That cut out both the Church and the universities. Every time, the crackdown was really about protecting power, just dressed up in religious words. So the practitioners went underground. Some were killed. The Inquisition burned people for far less than practicing ceremonial magic.
The tradition kept coming back. It resurfaced when the Renaissance rediscovered the Corpus Hermeticum, picked up speed with the 17th-century Rosicrucian pamphlets, spread through the Masonic networks of the Enlightenment, bloomed in the 19th-century revival (Eliphas Levi, Helena Blavatsky, the Golden Dawn), and carried on through many different movements in the 20th century. Each return says the same thing: people keep sensing that the official story of reality does not cover everything that is real. At its heart, this is the tradition of people who refused to let the official authorities have the last word on the mind, on reality, and on the ways a person can grow their own awareness. That refusal is not automatically more trustworthy than the authorities — the occult world has its own rigid dogmas, its own hierarchies, and its own abuses. But the refusal itself — the insistence on checking things for yourself instead of taking an institution's word — is the tradition's deepest and most lasting gift.