Rodney Collin (26 April 1909 - 3 May 1956) was a British writer in the area of spiritual development. His work was heavily influenced by his teacher P. D. Ouspensky and G. I. Gurdjieff and their system of spiritual development. Collin was one of the most well-known of Ouspenky’s students and a prolific writer. In addition to his best-known work, The Theory of Celestial Influence, Collin’s other work includes The Theory of Eternal Life, which uses some of the ideas of The Theory of Celestial Influence as a point of departure to formulate a theory of the cycles and potentials of souls, e.g. reincarnation, and The Theory of Conscious Harmony and The Mirror of Light, which are more spiritual explorations of humanity—faith, acceptance and forgiveness—in contrast to the philosophical scope of his earlier works.