Book excerpt: Practical Yoga Psychology is a guide to applying the principles of yoga to understanding the human mind and character. The book relates the practice of yoga to the principles and practice of psychology. Psychology is a science that tries to understand how the human mind functions. It tries to explain individual human traits, the behaviour of a person, the way they relate to other people, their surroundings and the world in general. The character and behaviour of a person is studied not just for an abstract understanding but also to find ways in which each person can improve relationships, improve the way they interact with the world and thus enhance their life experience.The science of yoga studies the human soul. In the view of yoga, it is not the body and mind that experience life. It is the soul that undergoes all these experiences through the body. Yoga classifies the character of a person based on the three Gunas, Tamas, Rajas and Sattva.Tamas is inertia, Rajas is passion and action and Sattwa is purity and balance. Yoga also studies the influences of the various chakras on the body and mind of a person. The chakras are centers of concentrated energy. The book explains the core qualities inherent in each chakra.