Ch 18 Yoga of Single-pointed Surrender (Part 8)
Impurities comprise impressions carried over from many lives, or natural temperaments — different tastes, wavering wants and infatuations, etc. Thus, the unconscious tastes and impressions from past lives are the impurities. Some of them are to be suppressed and purged. Others are to be experienced fully and then only can they be done away with. Purifying the sattva means eradicating the past impressions. This happens when they are indulged and used up in dealings with the world.