Wiktionary
n. philosophia perennis.
Wikipedia
The Perennial philosophy , also referred to as Perennialism, is a perspective in the philosophy of religion which views each of the world's religious traditions as sharing a single, universal truth on which foundation all religious knowledge and doctrine has grown.
Agostino Steuco (1497–1548) coined the term philosophia perennis, drawing on the neo-Platonic philosophy of Marsilio Ficino (1433–1499) and Giovanni Pico della Mirandola (1463–94).
In the early 19th century this idea was popularised by the Transcendentalists. Towards the end of the 19th century the Theosophical Society further popularized the concept under the name of "Wisdom-Religion" or "Ancient Wisdom". In the 20th century it was popularized in the English-speaking world through Aldous Huxley's book The Perennial Philosophy as well as by the strands of thought which culminated in the New Age movement.
Usage examples of "perennial philosophy".
Initiation is the discovery of the underlying and perennial philosophy.
This is the core philosophy that lies behind Shamanism, Buddhism, Taoism, this is the perception of the perennial philosophy, and I believe that using the lessons of the 20th century -- what was learned at Auschwitz and in the Haight-Ashbury, and at Alamogordo and Nagasaki -- using the lessons of the 20th century, the new youth culture can at least create a viable human alternative.