The Skin As A Semi-Permeable Membrane
If we’re able to feel our skin breathing – in the way described above – this means we’ve cultivated the capacity to spread our awareness out evenly across the entire surface of our physical body. We’re now able to experience directly, at a feeling level, the skin as something like a sack embracing the contents of our physical body.
But a sack that can breathe, and can “eat” lotion and other things that we feed it, is a pretty special sack. As it turns out, the skin, in a healthy state, acts as a semi-permeable membrane. What does this mean? It means that some things, but not others, are allowed to cross its boundaries.
This function – of letting useful substances in, and keeping harmful substances out – is associated also with Wei Qi: the “protective qi” described in Chinese Medicine. A healthy Wei Qi depends, for one, upon the capacity of the skin to both breathe and to sweat. When our bodies manifest a “fever” this is, in the language of Chinese Medicine, the activation of the Wei Qi: our bodies are attempting to expel the pathogen – to bring it to the surface and then out of our body.
One way to play with the skin as a semi-permeable membrane is to imagine, first, that your skin is something like aluminum siding: basically impenetrable. Next, draw forth an experience of “having no skin.” These are the two extremes: being completely closed, or completely open. Now, find something in between the two – a sense of the skin as being able to breathe, but also to keep out what is best kept out.
Expanding The Boundaries
Another fun practice is to explore the boundaries (the “skin”) of our more subtle bodies. To begin, spread your awareness out over the entire surface of your skin. Feel it hugging your physical body. Now, imagine that your body is something like a balloon, which you’re now going to inflate, to a larger size. Feel the boundaries of your body expanding, evenly in all directions.
Another way of doing this practice is to imagine that you are a baby chick, still inside the egg – feeling out to the boundaries of that egg. Or that you are still in your mother’s womb – feeling out to explore the contours of the uterus.
As you play with this, stay with the knowing that the contours, the “skin” of even these more subtle bodies, like that of your physical body, have the quality of being semi-permeable membranes. We can feel safe within them, yet at the same time allow for a healthy interchange with the outside environment -- the larger contexts of our world.

