R. Swinburne Clymer (1878-1966) was an American Rosicrucian. He reached the rank of Grand Master in 1905 and became the Supreme Grand Master of Fraternitas Rosae Crucis in 1922, serving as such until his death. The Mysteries of Osiris describes itself as "Setting forth the symbolism, mythology, legends and parables beginning with the outer religious systems of the Egyptians, primarily based on The Drama of the Heavens ; together with the Inner or Esoteric Interpretations as taught in the lesser and greater mysteries throughout the ages, including the present.