All beings subsist on nutriment - this, according to the Buddha, is the one single fact about life that, above all, deserves to be remembered, contemplated and understood. If understood widely and deeply enough, this saying of the Buddha reveals indeed a truth that leads to the root of all existence and also to its uprooting. Here, too, the Buddha proved to be one who saw to the root of things. Hence, it was thought useful to collect his utterances on the subject of nutriment, together with the instructive explanations by the teachers of old, the commentators of the Pali scriptures. The laws of nutriment govern both biological and mental life, and this fact was expressed by the Buddha when speaking of four kinds of nutriment: edible food, sense-impressions, volitions, and consciousness. It is hunger that stands behind the entire process of nutrition, wielding its whip relentlessly. The body, from birth to death, craves ceaselessly for material food; and mind hungers as eagerly for its own kind of nourishment, for ever new sense-impressions and for an ever expanding universe of ideas.