I remember an episode from my early childhood where I was trying to envision something. I knew that if someone told me a story, images would dance before my inner vision, and I would see them with great clarity. But when I tried to do so deliberately, there was only blackness, or a faint contour of the object.
What I was specifically trying to imagine was a green leaf. The harder I tried, the worse my results were. It was as if all that concentrating on concentrating was taking focus away from the actual task. Then, suddenly, while I was relaxing, images would swim before my inner vision, and the leaf would come too.
As time went on my powers of imagination grew, but only in the normal directions. I could see a tree, or many people, but things that were beyond my knowledge was outside of the scope of my imagination. And there was especially one whole dimension that elluded me. That of scale.
I might have been able to conjure a leaf, but could I ever see this?
These are the male sex organs of a dandelion. They are called anthers, and are filled with pollen ready to be picked up by a bumblebee and transferred to another plant. It is possible to see these structures, but to envision them at this detail is something that can only come with the aid of imagery and knowledge.
As Richard Dawkins once said in a televised lecture; Humans simply live on the human scale, the just so scale. The things that are tiny we don't really notice. We look at ants and think that they are small, but we have no idea about the real scale of bacteria. Or indeed, how they differ in scale. The largest is just about visible to the naked eye, up to a third of a millimeter long. The smallest, a mycoplasma, is 1500 times smaller. That is about the relationship of your size to that of a small rat. A rat, a scavenger of a city.
You, yourself is of course a city. A colony of cells, each bigger than most bacteria, and some of them capable of living a few hours after you are dead. They share, probably at about an equal rate, their life with the rats of the body, the bacteria. Okay. So bacteria actually serve a host of useful functions in the body, to the degree that mother's milk actually seems to foster bacterial growth in the gut of the infant.
The metaphorical switch of looking at the body as a city is only possible with an imagination of the depths of scale; and nothing of what we've been talking about, except for those things as a whole, is visible to us. Throught knowledge we may delve even deeper to imagine the atomic structure of our dna, watery blood or the fatty lipid membranes that cover our cells.
An imagination of depth allows us to investigate the same things, but over and over. Like the cells relation to the body, we can look at the body's relationship to it's friends, your friends. See you as groups, as the cells of a city; The doves serving the useful function of picking up scraps of food that would otherwise rot in the streets, but otherwise being quite irritating...
What allows these strange hangers on anyway? What is it about these systems that allow smaller freeloaders. Perhaps that there is a surplus of energy that is negligible to the bigger entities, but not to the smaller. And that, since this energy loss is then serving a useful function through the symbiotes it has not been selected against evolutionarily? I don't know, but such comparisons are rich with potential areas of study.
One of the first people to realize the modern version of this was IBM mathematician Benoit Mandelbrot. From observing nature he found that many patterns in nature were self similar. That is, a thing at one scale looks the same as itself at a lower scale. An example of this is most trees. Pluck a branch from a tree and set it on the ground. Quite often it will mimic the overall structure of the tree. The same tree-like structure of self similarity can be found in the circulatory system; with thick blood vessels branching out until they reach the smallest capillaries.
Mandelbrot was less about looking into the body, and emphasized the difference between seeing things close up and from far away. The description given from your perspective will depend of the nearness your are currently at. A house seen from a kilometre away will be drawn on a piece of paper as a dot; but from 1cm it is the color and roughness of the paint which is described.
Analogies up and down the scale are easy and fun to pull of; They are capable of revealing the degree of self similarity of elements at all the scales, and they allow us to take a center stage in this whole process. At least the us that is doing the justification.
If a cell wrote this essay, it might very well talk of the body as we do the city. If an atom wrote it, it would talk of itself as a conglomerate of insignificant quarks, and clothe itself in the glory as it's role is a kalium messenger in a synapse, in the spiral arm galaxy known as the corpus callosum! In fact, that very atom is probably now playing an integral part of writing this essay; thought it can't possibly know that, it's an atom.
However, if that atom can't know it's writing this article; then neither can the one beside it, or the one beside that - or any other atom in my brain. Except, I DO know that I'm writing this essay; and my brain is only made of those atoms, so they must know. At least a few of them must know.
And there I run off again, on another adventure of scale. Those are the kinds of thoughts that depth vision affords. I think this kind of imagination is incredibly valuable, like that view of the dandelion, whose beauty is apparent both as a field, as a flower and as a forest of anthers.