In regard to the method and the means of Bhakti-Yoga we read in the commentary of Bhagavan Ramanuja on the Vedanta-Sutras: "The attaining of That comes through discrimination, controlling the passions, practice, sacrificial work, purity, strength, and suppression of excessive joy." Viveka or discrimination is, according to Ramanuja, discriminating, among other things, the pure food from the impure. According to him, food becomes impure from three causes: (1) by the nature of the food itself, as in the case of garlic etc.; (2) owing to its coming from wicked and accursed persons; and (3) from physical impurities, such as dirt, or hair, etc. The Shrutis say, When the food is pure, the Sattva element gets purified, and the memory becomes unwavering", and Ramanuja quotes this from the Chhândogya Upanishad.