The book 'World's Great Saints & Yogis' by Sh. Dharam Vir Mangla is not only a rich source of information about them, but also compel us to re-think scientifically about their miracles. Miracles by saints are neither myths nor impossibilities. Scientists have been unreasonably ignoring the miracles performed by them as these are beyond their comprehension. This book encourages and promotes our thinking to understand the miracles better. If some of the scientists and doctors start their research work on their miracles, it will help in better understanding and curing many psychological and mental diseases due to emotions. This book will surely help them in their research work. From time immemorial India has been a land of great miraculous saints, Avatars and yogis. Eighteen Purana are the evidence to it. To ordinary mind these looks impossibilities, but with higher achievements in modern sciences these look true and explainable too. No scientific theory is fully explainable unless we accept existence of God, Atma (soul), Death, rebirth, law of Karma etc.Our advance scientific mind is not satisfied by simply reading Gospels (verses written by ordinary persons on the basis of Gossips). There are at least 15,500 Gossips stored, ignored by Vatican city. Why?