The book throws light on the most distinguishing features of Hindustani Music System dealing with Time Theory Concept or practice of assigning stated time of the day or night or any season prescribed for singing/playing a particular Raga. This concept according to ethnomusicological aspect is only found in Hindustani music among the World music cultures. This practice has existed in India from time immemorial. Our Sanskrit scholars have uniformly stuck to this practice. Our music passed through numerous Transformations during the last several centuries, but time Theory Practice has been scrupulously maintained. Our current music has outgrown the old Shastras, but still we find clear tendency to stick to Time Theory. This seems to be a most Indigenous and mysterious concept. Although good amount of papers and chapters have been written on the aspect of time-theory, but this book deals in detail with the psychological and Philosophical concept of Hindustani Ragas from the very beginning.