A Latin phrase with four distinct careers, kept apart in the perennialism project's disambiguation. (1) Agostino Steuco coined it (De perenni philosophia, 1540) for the thesis that one God-given wisdom, revealed at the beginning, persists through the ancient philosophers into Christianity. (2) Leibniz took the term over — the first philosopher to use it without crediting Steuco — recasting the primordial truths as seeds to be developed by philosophical progress. (3) Aldous Huxley's The Perennial Philosophy (1945) made it the name of an experiential mystical universalism: a divine Reality accessible in mystical experience across all religions. (4) The Traditionalist School of Guénon and Schuon holds a metaphysical version — a single primordial tradition transmitted only through the orthodox revealed religions — and rejected Huxley-style syncretism. Same phrase, four lineages: a statement about 'perennialism' must say which one it means.[1] [2] [3]