瑜伽論記 16.346

16.346

答意業為正行，食為緣助緣，助中多分用者立食，通力雖助，然四食用多，故但立四，食又四食用易覺知故。又身念住觀觸，觸生受故，法念觀思，心念觀識。又一日資養故，唯此四應顯為食辨趣有無中，子注云：此據正地獄無有段食，亦邊地獄亦有段食。故六十六云：若麁段食五趣可得，此於一分各別那落迦非大那落迦。

The answer is: Mental karma is the primary cause, while food is an auxiliary condition. Among auxiliary conditions, that which has a predominant function is established as food. Although the power of supernormal faculties assists, the function of the four foods is frequent; therefore, only four are established, and moreover, the function of the four foods is easy to perceive. Furthermore, the mindfulness of the body contemplates contact, because contact generates feeling; the mindfulness of phenomena contemplates volition; and the mindfulness of mind contemplates consciousness. Moreover, since they provide daily nourishment, only these four should be revealed as food. In distinguishing presence and absence among the destinies, the commentary by [Master Jing's] disciple says: This is based on the primary hells having no morsel food, while the marginal hells do have morsel food. Therefore, Fascicle Sixty-Six states: 'Coarse morsel food is found in the five destinies; this refers to a portion of the isolated naraka, not the great naraka.'