This book is based on a transcript of a lecture by Swami Ranganathanandaji Maharaj, the 13th President of the Ramakrishna Order. The book explores the nature of a human being by bridging modern scientific research (medicine and neurology) with ancient spiritual wisdom from the Upanishads. Originally delivered as a talk in the United States, the lecture was painstakingly transcribed by a devotee from Delhi and later edited by Swami Atmashraddhananda and other volunteers. Aim for this book is to provide seekers with profound, fresh insights into the deeper nature of human personality.