Yoga practice as described in Patanjali's Yoga Sūtra is the main theme of this chapter. Stanza by stanza translation of and commentary on each of the sutras in the second part of Yoga Sūtra are given in psychological terms. This part begins with description of action-based practical yoga, appropriately called Kriya Yoga. It is a threefold practice involving (a) ascetic practices, (b) spiritual wisdom, and (c) unwavering faith in God. Ascetic practices such as Tapas are meant to promote self-discipline. Spiritual wisdom is gained by self-study (svādhyāya). Faith in God promotes surrender of the self through celestial love and thus helps to overcome the ego. Self-surrender leads one to undertake action for its own sake rather than aspiring for its fruits. The sources of suffering in human condition are called kleśas in Yoga. Kriya Yoga is meant to attenuate kleśas, which corrupt the mind and hinder the practice of yoga. Kleśas are five in number. They are (1) ignorance (avidya), lack of true knowledge, (2) egoness (asmita), the feeling of I-ness, (3) attachment (rāga), (4) aversion (dveṣa), and (5) will-to-live (abhiniveśa).