philosophia perennis (Latin ‘perennial philosophy’), a supposed body of truths that appear in the writings of the great philosophers, or the truths common to opposed philosophical viewpoints. The term is derived from the title of a book (De perenni philosophia) published by Agostino Steuco of Gubbio in 1540. It suggests that the differences between philosophers are inessential and superficial and that the common essential truth emerges, however partially, in the major philosophical schools. Aldous Huxley employed it as a title. L. Lavelle, N. Hartmann, and K. Jaspers also employ the phrase. M. De Wulf and many others use the phrase to characterize Neo-Thomism as the chosen vehicle of essential philosophical truths. R.M.