" Patañjali describes the fluctuations, modifications and modulations of thought which disturb the consciousness, and then sets out the various disciplines by which they may be stilled. This has resulted in yoga being called a mental sadhana (practice). Such a sadhana is possible only if the accumulated fruits derived from the good actions of past lives (samskaras) are of a noble order. Our samskaras are the fund of our past perceptions, instincts and subliminal or hidden impressions. If they are good, they act as stimuli to maintain the high degree of sensitivity necessary to pursue the spiritual path. Consciousness "

― B.K.S. Iyengar , Light on the Yoga Sūtras of Patañjali