In this world there exist four main classifications of diet:
(1) A lax diet conforming to habitual desires and taste preferences. People following this diet sway back and forth erratically in response to whims and fancies. This diet could be called self-indulgent, empty eating.
(2) The standard nutritional diet of most people, proceeding from biological conclusions. Nutritious foods are eaten for the purpose of maintaining the life of the body. It could be called materialist, scientific eating.
(3) The diet based on spiritual principles and idealistic philosophy. Limiting foods, aiming toward compression, most “natural” diets fall into this category. This could be called the diet of principle.
(4) The natural diet, following the will of heaven. Discarding all human knowledge, this diet could be called the diet of non-discrimination.
People first draw away from the empty diet which is the source of countless diseases. Next, becoming disenchanted with the scientific diet, which merely attempts to maintain biological life, many proceed to a diet of principle. Finally, transcending this, one arrives at the non-discriminating diet of the natural person. (Excerpt from The One-Straw Revolution)