First we call to mind the Earth element within ourselves. The Earth element is everything solid and resistant, everything that gives us form. When I’m teaching this practice I encourage students to notice first of all those aspects of the body that they can directly experience: the physical presence and weight of the body, the feeling of the sitting bones pressing into the cushion or bench, the hands resting on the lap, the knees on the floor, the teeth. We simply notice these experiences of solidness.
But as well as noticing those sensations we enter into an imaginative exploration of the rest of the body. Even though we can’t experience them directly, the sutta encourages us to call to mind the flesh, sinews, bones, bone-marrow, kidneys, heart, liver, diaphragm, and every other conceivable solid matter in the body, right down to the feces in our intestines. We don’t think about these things but simply call them to mind, knowing they are there and experiencing them in the mind’s eye.
Having reflected on the Earth element within, we now call to mind the Earth element externally — everything that is solid and resistant outside of ourselves — starting with the floor upon which we sit, then expanding outward to recall buildings, vehicles, roads, mountains, rocks, pebbles, soil, the bodies of other beings, trees, wild plants and crops growing in fields. Again we don’t aim to start trains of thought, but simply aim to evoke memories in the form of sensory impressions, letting images, sounds, and tactile sensations come to mind.
Then we reflect that everything solid within the body and everything solid externally is the same Earth element. There’s really no “me” Earth element or “other” Earth element — it’s all the same stuff. We normally think of our form, our body, as being us, as being ourselves, but here we recollect how everything of the Earth element that is within us comes from outside and returns to the outside.
Being of a scientific bent — and I think the Buddha was too — I often call to mind the process of conception. My body started with the creation of one cell from the fusion of a sperm and an egg from my parents, who are not me. The fertilized ovum divided and grew into an embryo as it absorbed nutrients from the world outside — from my mother’s bloodstream, but ultimately from the plants and animals she ate. And from that point on in my life, every molecule that has contributed to the earth element in this body similarly has come from outside. We can visualize the flow of the Earth element from fields and soil into the body. There’s not a single molecule of solid matter within this body that is self-originated. It’s all borrowed.
And we have to give it back. In fact we constantly are giving it back, every moment of our lives. The Earth element within us is constantly returning to the outside world. We shed hairs and skin cells, and we go to the bathroom and defecate. Solid matter is combusting within the body and being exhaled. Even our bones, which we may think of as the most solid and enduring part of the body, are involved in never-ending process of being dissolved and rebuilt. There are cells in your body that have no other function than to dissolve the surrounding bone, while other cells are involved in building it back up again. Even your bones are processes rather than things.
So the Earth element within is borrowed, and it’s always returning to the outside world, flowing through us like a river. And as we recollect the Earth element flowing in this way, we can reflect: “This is not me, not mine, I am not this.” There’s not really even any question of “letting go.” The earth element never was “us.” It never was “ours.” We never were holding on to it because how can we cling to something that’s flowing?
The Earth element provides the paradigm for the remaining physical elements, which are all treated in the same way — recollecting the element within us, recollecting the element outside of us, reflecting that everything that is “us” is really just borrowed from the outside world and constantly returning to it, and finally noting, as we contemplate the element flowing through us that this is not me, not mine, that I am not this.