This book is excellent for the developing mind, but I don't think it goes far enough in my estimation. Based on the pitiful display of the mental performance of the average person, it is perfectly obvious that we only use a fraction of our brain power when you compare the ordinary person with a highly skilled person. The book talks about how consciously using only a small percentage of your brain will eventually contribute to a fading memory, a loss of your sense of hearing, taste, smell, etc. and a very skewed reasoning ability in your latter years. It discusses how thinking can become extremely distorted due to a lack of emotional discipline resulting in many older people having their reasoning mixed with discordant, child-like emotions. It openly declares that brain degenerative diseases are brought about through lack of diversified brain use, which flies in the face of current science trying to attribute genetic or biological reasons for such maladies. It makes claims that all of this loss of memory, loss of sensory ability, loss of logical thinking and display of infantile emotions can be averted with deliberate mental exercise. The book further states how difficult it is to attribute a definitive percentage of brain use to any particular person, because it is always changing throughout a person's life, but that the average person's brain usage is on a continual decline after early adulthood. It points out that there is a big difference between someone that uses his complete brain in a diversified way throughout his life and someone who does not, the latter having large atrophied dead zones in the brain upon post mortem examination in old age. In my opinion, the missing feature of the book though is the spiritual connection. The book does have a spiritual overtone (not religious) when it references certain exercises, but it does not directly attribute the spiritual reasons that some exercises work for some people but not for others. Granted it might be very unscientific to mention spirituality, but in some circles this is the only explanation that certain phenomenological feats are possible for the more skilled individuals.