Yogācārabhūmi-śāstra, Volume 34 (29)

Original text: 云何观察库藏变异无常之性。谓由观见种种库藏。一时盈满一时灭尽。见此事已。便作是念。如是诸行。其性无常。余如前说。云何观察饮食变异无常之性。谓由观见种种饮食。一时未办一时已办。一时入口牙齿咀嚼。和杂涎唾细细吞咽。一时入腹渐渐消化。一时变为屎尿流出。见此事已。便作是念。如是诸行。其性无常。余如前说。

Explanation: How does one observe the impermanent nature of the transformation of storehouse phenomena (treasury phenomena)? One observes that various storehouses are at one time full and abundant, and at another time depleted and exhausted. Having observed these phenomena, one then has this thought: such formations as these are truly impermanent in nature. How does one observe the impermanent nature of the transformation of food phenomena? One observes various kinds of food and drink: at one moment they are not yet prepared, at another moment they are prepared; at one moment they enter the mouth and are chewed by the teeth, mixed with saliva and slowly swallowed; at another moment the food and drink enter the belly and are gradually digested, and then are transformed into feces and urine and excreted. Having observed these phenomena, one then has this thought: such formations as these are truly impermanent in nature.