Macrobiotics practitioners say "every front has a back", and nowhere is this more true than in our body tissue.
Health is another word for balance: life is fluid and dynamic. If we reach a condition of stasis, we're dead. The nourishing of life is primarily about the creation and maintenance of balance (spiritual, emotional, mental, physical, communal). Giving and receiving, breathing in and breathing out, consuming and eliminating, acquiring and letting go, beginning and ending, giving birth and dying. My all time favourite quotation (Toinette Lippe), "Problems arise where things accumulate", applies.
With this in mind, I've been thinking about the body and its balancing pairs — two ears, two eyes, two arms and two legs, two lungs, and so on. Even the bones in our spine divide like wings. The pelvis, the rib-cage — the body is a complete set of balanced halves.
In our time of foetal development, so I've read, there comes a point of tissue division that gives rise to the nervous system and the gut. Now, I suppose at that early stage of development there's a sense in which everything comes from everything else and all of it comes from the fusion of egg and sperm, male and female, creating a fundamental balance of opposites in our beginning. Even so, the gut and the central nervous system have a particular balancing reciprocity. They emerge from the same foetal tissue at a particular point of development, and are connected by the long vagus nerve that runs down between them. This is why the gut has so many neurons in it, and is the seat of much of the process we give the name "thinking".
And if you visualise them, you can see that the central nervous system and the gut remain a balancing pair, front and back.
The central nervous system, held aloft by the bones of the spine and skull, runs in a line up the back, like a flower or a gourd on a stem. Similarly, the gut is a long line, the intestinal wall in sections as the bones of the spine are in sections, the lumen of the gut encased within the intestinal wall as the cerebral tissue and fluid are encased within the spine. As the spine flowers into the brain (or is the tail of the brain, depending which way you look at it), so the intestine is the tail of the stomach. I have a feeling that the direction here is also a matter of balancing opposition – that energy flows up the spine to the brain and down the gut from the stomach, but I'm not sure about that. The gut of course is folded and cradled within the musculature of the abdomen, the back and the perineum, and nestled into the pelvis, just as the central nervous system is held within the spine and skull. Another opposing pair; soft and hard.
Along the spine is located the invisible system of energy vortices known as "chakras", and they correspond to the soft organs stationed along the body pathway — (leaving aside the top one) eyes, breathing apparatus, digestive organs, reproductive organs and eliminative organs. That last one connects everything up, because the root chakra that sits at our perineum is about nourishment as well as elimination, so it brings us back to the mouth where the cycle of nourishment begins.
The crown chakra at the top is where our dependency from heaven passes — our string to the sky that keeps us grace-full and upright. In infancy it is open and soft (the fontanelle), and even in old age we keep the crack the light shines through and are nourished by the light of heaven. Physically this is expressed in the pituitary gland, responsive to the waxing and waning of the light, governing the all-important endocrine system that determines the directional flow of our health (eg, slowing or speeding up, getting fatter or thinner, masculinising or feminising, waking or sleeping etc).
We are fearfully and wonderfully made. Every front has a back, and this is so throughout the whole natural world — even in aspects we think we have made, like politics and economics and religion. It breathes in and breathes out, gives and takes, fills and empties; and if it stops doing that, it dies and subsides to nourish new life.