This small book has two lectures of Swami Vivekananda:
Powers of the Mind given in Los Angeles, Calif. on Jan. 8, 1900
and
Concentration and Breathing

(excerpt from Powers of the Mind))
The science of Yoga claims that it has discovered the laws which develop the personality, and by proper attention to those laws and methods, each man (or woman) can grow and strengthen his or her personality. This is one of the great practical things and is the secret of all education.