Habit comes out of practice, and forms character by degrees, and eventually works out destiny. Therefore we must practically sow optimism, and habitually nourish it in order to reap the blissful fruit of Enlightenment. The sole means of securing mental calmness is the practice of Zazen, or the sitting in Meditation. This method was known in India as Yoga as early as the Upanisad period, and developed by the followers of the Yoga system.[FN#243] But Buddhists sharply distinguished Zazen from Yoga, and have the method peculiar to themselves. Kei-zan[FN#244] describes the method to the following effect: 'Secure a quiet room neither extremely light nor extremely dark, neither very warm nor very cold, a room, if you can, in the Buddhist temple located in a beautiful mountainous district. You should not practise Zazen in a place where a conflagration or a flood or robbers may be likely to disturb you, nor should you sit in a place close by the sea or drinking-shops or brothel-houses, or the houses of widows and of maidens or buildings for music, nor should you live in close proximity to the place frequented by kings, ministers, powerful statesmen, ambitious or insincere persons. You must not sit in Meditation in a windy or very high place lest you should get ill. Be sure not to let the wind or smoke get into your room, not to expose it to rain and storm. Keep your room clean. Keep it not too light by day nor too dark by night. Keep it warm in winter and cool in summer. Do not sit leaning against a wall, or a chair, or a screen. You must not wear soiled clothes or beautiful clothes, for the former are the cause of illness, while the latter the cause of attachment. Avoid the Three Insufficiencies-that is to say, insufficient clothes, insufficient food, and insufficient sleep. Abstain from all sorts of uncooked or hard or spoiled or unclean food, and also from very delicious dishes, because the former cause troubles in your alimentary canal, while the latter cause you to covet after diet. Eat and drink just too appease your hunger and thirst, never mind whether the food be tasty or not. Take your meals regularly and punctually, and never sit in Meditation immediately after any meal. Do not practise Dhyana soon after you have taken a heavy dinner, lest you should get sick thereby. Sesame, barley, corn, potatoes, milk, and the like are the best material for your food. Frequently wash your eyes, face, hands, and feet, and keep them cool and clean. [FN#243] See Yoga Sutra with the Commentary of Bhoja Raja (translated by Rajendralala Mitra), pp. 102-104. [FN#244] Kei-zan (Jo-kin), the founder of So-ji-ji, the head temple of the So To Sect of Zen, who died at the age of fifty-eight in 1325. He sets forth the doctrine of Zen and the method of practising Zazen in his famous work, entitled Za-zen-yo-jin-ki.