Robert Collier Robert Collier (1885-1950) was an American author associated with the New Thought movement, best known for his writings on the relationship between belief, imagination, and personal achievement. His works, including The Secret of the Ages, have influnced generations of readers interested in the practical application of mental and spiritual principles. Collier's writing combines philosophical reflection with direct, accessible guidance, contributing to the development of modern self-development literature. Read More Read Less