In recent years, a keen interest has emerged in the world of science regarding the relationship between the biological and the psychological aspects of the mind. How can the neural activity of the brain create thoughts, memory, feelings, and emotions? The answer to this question is the subject of this book. Jorge Angel M.D. posits that, although the mind is the byproduct of the firing of neurons in different parts of the brain, it is also the organizing principle of brain activity. The brain and the mind have a symbiotic relationship that is present throughout the life span of the individual. In an effort to find answers to the riddle of the mind-brain relationship, Dr. Angel describes his personal experiences of many years in the practice of the healing arts, and he draws on a lifetime of study into the biology of the brain. The author maintains that the mind is much more than consciousness. Consciousness has been described metaphorically as the small tip of an iceberg floating in a sea of unconsciousness. Dwelling on the evolutionary development of the brain, he explains how intellectual experience arises from the activity of cell aggregates in the residual reptilian, residual mammalian, and rational parts of the brain that we have inherited from our animal ancestors through billions of adaptive trade-offs over millions of years. The human mind is one of the last unresolved mysteries in the world of science. This book provides a meaningful insight into the nature and function of the mind in normal subjects and their ability to think, feel, and remember. It also portrays in detail the changes that can be brought on the mind of humans by an assortment of psychological and neurological disorders.