Lectures on the Sūtra of the Collection of the Father and Son (Pitāputrasamāgamanasūtra) (25)

What is the internal water element?

Original text: 大王。云何内水界。谓此身内。所有执受。湿润等性。涎唾脂髓。脓血便利。为内水界。

Explanation: Great King, what is the internal water element? It is all the moist nature within the physical body, such as saliva, tears, sweat, nasal mucus, fat, pus, blood, urine, and feces—all of these belong to the internal water element.

The earth element is divided into the external earth element and the internal earth element; the internal earth element is the hardness within our physical body. The water element is also divided into the internal water element and the external water element; the moist nature within the body is the internal water element. The characteristic of water is its moistness. For example, when we become emotionally stirred, our eyes well up with tears; even though the tears have not fallen, there is moistness within—that is the nature of water. When the body gets hot, we sweat; sometimes there are no visible beads of sweat, yet there is still a damp quality—that is the nature of water, and when sweat actually flows out, it is even more evidently the nature of water.

There is also water within the skin. If there were no water in the skin, it would become dry and wrinkled, losing its moistness. In fact, there is also the water element in the hair, in the nails, in the bones, and in the flesh; the internal organs all possess the nature of water, and the water element pervades the whole body, inside and out. Without the water element, life could not be sustained. Every organ possesses the four great elements—the elements of earth, water, fire, and wind—and together they combine to form the various different organs; it is only that the proportions of the four great elements differ from organ to organ. When the earth element occupies a larger proportion, the material manifests hardness; when water occupies a larger proportion, moistness and softness are revealed. Because the proportions of the four great elements differ, the materials formed are different.