...Our bodies are like tubes or levers or computers, but they are, above all things, like bags. Bags that are stuffed in other bags, stuffed in still more bags. Our bodies are nesting bag situations like the used bags stuffed under your kitchen sink, with the added bonus of thumbs and anxiety. The analogy gives me clarity—when I have trouble understanding anatomy, I look for the bag. It gives me context—figuring out how to replicate or get inside our various bags is a critical part of modern medicine. Finally, it gives me comfort. Life isn’t that complex after all. It’s just a series of bags, getting more and more fancy and specialized....

Much like you may with the bags under your kitchen sink, cells even reuse and recycle some of their bags. Tiny bags called vesicles contain chemical messengers. Those bags dump their contents outside the cell, and merge with the larger bag of the cell itself, only to get pinched off and reused again when more packaging is required. Life itself can be drilled down to bags: the first cell wasn’t a cell until it was separated off from the outside world—until it had a bag.

Bags aren’t just a thought exercise for insomniacs—but something our medical knowledge grapples with daily. Scientists and doctors are still studying and often trying to replicate our many natural bags. Some are studying how to make synthetic vesicles, to release chemicals where and when we want them. Others are trying to build artificial placentas for premature infants. Some bags might be allies, while others might serve more as worthy adversaries. It’s a constant fight for new medicines to get past our determined brain bags to cure our mental ills.

Sitting with my anatomy text, and waiting patiently for sleep, I find my many bags both wonderous and comforting. The world can seem endlessly complex, full of the things we should have known, the things we did or didn’t do well enough. But human life, the physical stuff that makes us love and hate and judge and care? It’s just bags all the way down.