Lecture Notes on the Sūtra of the Collection of the Father and Son (Pitāputrasamāgamasūtra) (Thirty-Seven)

The Bacteria Within the Physical Bodies of Sentient Beings

The fire element has the nature of heat and warmth. If there were no fire nature or temperature within the body, the food in our stomachs could not decompose and be absorbed by the body. Therefore, no matter how delicious the food and drink we eat may be, and no matter how complete their color, aroma, and flavor, once they enter the stomach, the fire nature in the body rots the food. The food and drink we consume, and the so-called nutrients we absorb, are extremely filthy and impure; thus one should not crave food and drink. If one frequently contemplates in this way on impurity, one can reduce the craving for food and drink.

In fact, upon careful reflection, our bodies, from top to bottom and inside to outside, are extremely filthy, covered with bacteria everywhere. The decomposition of food relies entirely on the bacteria's breaking down of what we eat. Without the help of bacteria, we could not absorb food. It is the bacteria that help us decompose, digest, and absorb; sentient beings can live normally only by relying on these beneficial bacteria. Therefore, there is no need to crave or be infatuated with our own filthy physical bodies, or with the filthy physical bodies of other sentient beings.

The Buddha said that the physical body of sentient beings is like a moving toilet, a large bucket of excrement, wrapped in a layer of smooth outer skin. If you peel off this layer of skin, inside it is a bloody, mangled mess, full of bacteria, and even the outer skin is teeming with bacteria. When the skin is peeled off, is this person still pretty and beautiful? It is all flesh, blood, sinews, and bones. Upon careful reflection, the physical bodies of sentient beings truly have nothing worth clinging to or craving—they are extremely filthy. If we had the divine eye (divyacakṣus), with our eyes functioning like a microscope to examine our skin and the inside of our bodies, we would find that both inside and outside are entirely bacteria—something our naked eyes cannot see, but which a microscope and the divine eye can. Those bacteria are also fighting among themselves; when the bacterial populations become unbalanced, skin diseases and other illnesses arise. Wherever the bacterial population is unbalanced, that is where disease occurs. When we feel hungry, it is also because the bacteria are hungry; when the bacteria need to eat, we want to eat, and thus we become gluttonous and greedy for food.