From Lectures on Yoga

Shaucha

Shaucha involves purity both of the body and the mind. Purity of the body is easily achieved but not purity of the mind. To achieve purity of the mind one should cultivate Smriti or mindfulness and Buddhi or discrimination. That is, one should always be aware of one’s thoughts and should learn to discriminate between pure and impure thoughts on the basis of whether they lead to greater freedom or greater bondage and ignorance. Sincerity and perseverance are essential in cultivating this Niyama.

Santosha

Santosha or contentment is a state of mind which is not dependent on one’s material status. A beggar can be as content, if not more so, than a king. Man’s desires are insatiable and no sooner is one fulfilled than another arises. The mind is, therefore, in a constant state of agitation. Tranquility is possible only through cultivation of Santosha. Contentment should not, however, lead to slackening of all effort. Efforts should stem from a sense of duty and service rather than from discontent and anticipation of the fruits of one’s efforts.

Tapas

Tapas has often been wrongly interpreted as excessive austerity and mortification of the flesh exemplified by hair shirts and beds of nails. In the Bhagavad Gita, the Lord Krishna clearly states that yoga is not for him who indulges the flesh nor for him who tortures it. Tapas literally means that which generates heat. This heat arises in one full of spiritual fervor, one with a burning desire for enlightenment. Acts which increase this spiritual fervor constitute Tapas. A simple life free from sensual indulgence, regulated fasting, chanting the name of the Lord, serving one’s fellowmen, all constitute Tapas. Through Tapas one develops strength of body and mind and the blaze of spiritual fervor burns brighter.

Svadhyaya

Svadhyaya is study leading to knowledge of the Self. This study begins with intellectual pursuit and understanding of the scriptures and other books of spiritual value. Rational acceptance of spiritual truths leads upon further reflection and meditation to intuitive insights and then to true understanding of these truths. These insights are supported by the study of the internal states of consciousness. Only then does knowledge of the Self begin to dawn on the aspirant.

Ishwara Pranidhana

Ishwara Pranidhana or surrender to the Ultimate Reality is possible only with infinite faith and dedication. Such a total surrender is achieved only with time, sincerity and perseverance. The ego has great tenacity and resists such a complete surrender. When the ego is transcended knowledge of one’s true nature is attained.