Commentary on the Sutra of the Compilation of Father and Son (49)

What is the internal space element?

Original text: Great King, what is the internal space element? It refers to the manifestation and growth of the skin, flesh, blood, and the like within this body, devoid of material obstruction. For instance, the eye sockets, ear canals, nostrils, throat, and the passage through which ingested food and drink pass, conveying flavors through the stomach and intestines, passing through unimpeded.

Explanation: The Buddha said: Great King, what is the internal space element? If the skin, flesh, blood, etc., within this body can manifest and grow without material obstruction, that is the internal space element. Material obstruction prevents the growth of skin, flesh, bones, and sinews, constraining them. The empty spaces devoid of substance, such as the eye sockets, ear holes, nostrils, throat, etc., constitute the space element. After swallowing and tasting food and drink, they enter the esophagus, pass into the stomach and intestines, are digested, and are then expelled. This pathway from the mouth through the esophagus to the stomach and into the large and small intestines is the space element, free from obstruction. If there were material obstruction, it would not be empty; food and drink could not enter the body, nor be expelled from it.

What is meant by the space element? Here, "space" (空, kōng) refers to voidness, the emptiness of nothingness, meaning vast and open. Within the internal body, where there is no skin, no blood, no flesh, and no obstruction, there is emptiness. Blood vessels have space within them, allowing blood to flow; the trachea is empty, enabling us to breathe; the stomach and intestines have a space element, allowing food to move within them; the body has space, enabling gases, liquids, food, waste, and the like to flow within, cells to divide, and muscles, bones, sinews, etc., to grow.

Within the body's cells, there are gaps and spaces, allowing the various particles within the cells to move along their respective orbits. Between particles within cells—such as electrons, protons, ions, nucleons, etc.—there are spaces, enabling various physical and chemical reactions to occur between particles, allowing cells to divide and grow, and the physical body to undergo changes. There are also spaces between cells, allowing inhaled oxygen to enter the body's cells to produce blood, which then flows within the body. The various spaces within the body are called the internal space element.

The six sense bases (六处) are form, sound, smell, taste, touch, and dharmas (mental objects). Each type of form (色法, rūpa-dharma) is composed of the four great elements (四大)—earth, water, fire, and wind—and also includes the space element (空大) as a constituent. Thus, form is composed of five great elements. Within form, there is space and void. The four material elements within form enclose space. Depending on the size of the space within the material form and the proportion of the space element, the density of the material form differs, resulting in different physical properties of the matter.

Furthermore, these six sense objects (六处色法) all manifest within the consciousness of the six sense faculties (六识心), forming images at the subtle sense faculty (胜义根) located in the hindbrain. Therefore, they belong to the internal six dusts (内六尘, internal sense objects). The space within the subtle sense faculty belongs to the internal space element. Where does the internal space element come from? When it comes, it has no source; when it goes, it has no destination.