This book excerpt, Secrets of Mental Supremacy, by W. R. C. Latson, M.D., provides a practical guide for developing mental power. The author emphasizes the importance of training the senses (perception) for building a strong foundation for mental development. He then explores the significance of memory, association of ideas, imagination, and concentration, arguing that each of these faculties can be cultivated and enhanced through specific exercises. Latson ultimately suggests that a complete understanding of oneself requires an integration of physical, mental, and spiritual aspects, akin to the state of mind referred to as "the Kingdom of Heaven." He further underscores the importance of regaining the simplicity, trustfulness, and tenderness of childhood in order to achieve true mental and spiritual fulfillment.