Manly P Hall On The Fourth Pythagorean Proposition.
Manly Palmer Hall (March 18, 1901 – August 29, 1990) was a Canadian-born author, lecturer, astrologer and mystic.
He is best known for his 1928 work The Secret Teachings of All Ages. Over his 70 year career, he gave thousands of lectures, including two at Carnegie Hall, and published over 150 volumes.
In 1934, he founded The Philosophical Research Society in Los Angeles, which he dedicated to the “Truth Seekers of All Time”, with a research library, lecture hall and publishing house.