As expounded in all ancient traditions and as is increasingly being rediscovered by modern medical research, the physical body is the gross material expression of a more subtle body. The body is surrounded by a nervous envelope through which disease must first penetrate before affecting the physical body. This book spells out in the words of the Mother the secret inner causes of health and disease. The methods of mastering the body's functioning in the light of a deeper knowledge of the subtler levels influencing the physical are expressed in direct, lucid language.