The final pair of design principles that Hemenway set out in his article have to do with reciprocity:
7. Look both ways before crossing. Everything works both ways. If the bank gives you 30 years to pay for your home, you give the system (the bank) 30 years of your life in indentured servitude. If energy can come in through a window, it can fly out a window. If it takes a lot of heat and time to warm a mass, it can give off heat for a long time. Death of individual cells is necessary for the life of other cells. What goes up must come down. Got it?
8.The gift must always move. This is the universal law of gifts. To survive and be well and joyous, we must transform and give away all gifts which come to us. This is how species of an ecosystem coexist. I accept the gift of oxygen from the trees and other plants and return it as carbon dioxide. We violate this principle when we accept food from the earth and do not return our urine and feces, but instead use it to contaminate water. To return a gift without transforming it to your nature is to reject it - it is an affront to the love of the universe.
I don't have any direct comparisons (at least none that I can think of just now) with the nervous system for these two features, other than perhaps the relationship the CNS has with the PNS (usually) or the relationship neurons and glia have with one another, or the relationships various parts of the accretion we call the human brain has with all the creature parts it evolved through in its evolutionary history.. and still has intact and functional..
Some might think, what about the body? Doesn't the nervous system have a reciprocal relationship with the body? Well, yes it does: if you had a hypothetical human "body" that you could stand before you, and you could remove all but one tissue system with the click of a mouse, (as you can sort of do at www.visiblebody.com ), and you clicked away everything but the bones and meat, yeah.. you'd still have a "body"... but it wouldn't work without a nervous system to run it - it would quickly fall over, die and rot.
If you clicked away everything but the nervous system, you'd still be able to recognize the person, the person would still have height and breadth and shape, but that two percent that was left would seem pretty insubstantial and wouldn't work very well without an energy source or its mesodermal "overcoat" to help it preserve its temperature. With no living struts or bungee cords to hold it up, its "mayday" output would go nowhere and do nothing; it would collapse to the floor, all its 72 km of nerves in a heap of tangled threads and cords, under the weight of a brain that would fall down plop onto the top of the pile as the spinal cord collapsed with no spinal column to tether itself inside of or maintain in an upright position. With no oxygen or energy coming into it from lungs and metabolism, it would quickly go unconscious and die, turn into a puddle of goo.
So yes, there is a basic survival relationship here. However, I think the relationship the nervous system has with the (mesodermal) body is only one of the large number of relationships it maintains within itself and its various levels of function, and I want to stay on track here - the post series is intended to be about the relationship or "reciprocity" between the unconscious brain and the conscious brain.
In the next post I'll start bringing material here based on Guy Claxton's book, Hare Brain, Tortoise Mind, and continue the composter metaphor.