Svādhyāya is the 4th Niyama or virtuous observance, which is the 2nd limb of yoga. It means self-study, self-reflection, or introspection of one’s body and mind, thoughts, speech and actions.
Study thy self, discover the divine. — Yoga Sutra, II.44
Through self-study, we discover our true nature. Who are we behind all the stories we create and the ideas we internalize about ourselves?
Discovering who we truly are emerges from a growing understanding of what we are not. Through meditation and self-reflection we gain insight into our conditioning and habits. We begin to understand the ways in which we cause ourselves and others to suffer. Through asana we engage in observation and get direct feedback from the body, breath and behavior. We see that we are not our bodies or what we think, feel or do. An exploration of wisdom teachings imparts us with the knowledge of great teachers throughout the ages. We benefit from what they learned through their own self-study.
Gradually, with patience and devotion, we shine the light of awareness into all the dark corners, chasing away delusion and illuminating reality. Obscurations are cleared to reveal our eternal essence which was there all the while, just waiting to be discovered.
…human body is cleansed by water, the mind is cleansed by truth, the soul by self-study and meditation, while understanding is cleansed by knowledge. – Vishnu Sutra, 22.92