In plain words
Man thirsts for Ānanda. The one who longs to attain Brahmānanda must first of all make his heart pure. The human heart, which should be an ocean of milk, has today become a home of sorrows and a centre of evil feelings. To strive to change the heart into a holy ocean of milk is the sādhaka's chief duty. The quality of milk is whiteness. When the heart holds the sāttvic quality, it is itself the ocean of milk. In that very ocean of milk Viṣṇu reclines. Only when the heart is pure does the Paramātma dwell in it. But man today gives room to tamoguṇa and rajoguṇa, pollutes his heart and turns it into an ocean of brine. To turn the ocean of milk into an ocean of brine is to go the wrong way. In the ocean of brine live sharks, crocodiles and whales: kāma, krodha, lobha, moha, mada and mātsarya. Making the heart a home for such vicious creatures is folly. The Paramātma is the One who reclines on the ocean of milk. That is, He dwells in the heart. So we must turn the heart into an ocean of milk. We must foster pure sattva and keep the rājasic and tāmasic qualities far away.
The health of the mind
The wise must try every day to examine their own hearts. They must enquire whether holy feelings are growing in the heart, or unholy feelings are thriving. When we perform our pūjās, through the mantras: ‘O deities, come! Enter into me!’ so we invite them. ‘O demons who are within me!