Knowledge, austerity, suspension of breath (pránáyáma), religious exercises of the Sandhyá, sun-light, moon-light, fire, water, air, earth, ashes, mustard-seed, wild produce of the earth, shade of a tree, the back and legs of a cow, a plough, a broom, sour things,* salt-water, mouth of a horse or goat, eating certain food, the lapse of time, milk, butter-milk, clarified butter, and the dung and urine of a cow.