The control of the mind is not a problem peculiar to religious aspirants; people in all walks of life need to control their minds if they are to succeed in their respective vocation. No fundamental work for the uplift of the individual or of the community can ever be done without the mind being controlled. This book, which sets forth the teachings of Vedanta and Yoga on the nature of the mind and ways of controlling it, is meant for one and all.
Change is always subjective. All through evolution you find that the conquest of nature comes by change in the subject. Apply this to religion and morality, and you will find that the conquest of evil comes by the change in the subjective alone. That is how the Advaitic system gets its whole force, on the subjective side of man.
-Swami Vivekananda