My first semester of medical school I went to the anatomy lab 2, 3, 4, sometimes more times a week. Sometimes twice a day. In our anatomy lab we were split into groups and each assigned a cadaver for dissection. Cadavers are people who donated their bodies upon death to science, we call them “donors” in our lab. The 20 donors in our lab were once 20 people who had the vision to let us, 120 aspiring doctors, disassemble the human body so that we could intimately understand how it fits together.

The idea of cutting apart a human, even if they are dead, is disgusting to most people—including all of us who showed up to anatomy lab the first day. It never got easier to dissect my donor. I spent a little bit of each hour in lab wondering who my donor had been in life and if she had any idea what happens in an anatomy lab when she decided to donate her body. Yet, now that I’m done with anatomy lab and have had months to stew on my experiences there, I can’t imagine not dissecting a cadaver as part of my training to become a physician. Let me share one, relatively low on the gruesome scale, experience to illustrate how profoundly moving and informative it was to be able to explore a human body piece-by-piece.

Toward the end our months in the anatomy lab it was time to open the skull and see the brain of our donor. Weeks before that we had dissected the spine, opening up the vertebral column so we could see what the spinal cord looked like. Each week of lab leading up to the day we opened the skull was spent tracing nerves from the spinal cord and brain to each section of the body we had examined. Nerves look like strings, specifically they look like white, cotton strings soaked in oil. We spent many hours memorizing the names of those strings (the nerves) and their paths through the body.

So, on the day we finally got to open the skull we understood how the brain was connected to every muscle and structure in the body. We knew intellectually how they were connected but, also, physically how they were connected. Our hands had followed the course of many nerves until their routes were as familiar as the path of a zipper on a favorite jacket. We could imagine the journey of the nerves through the body without seeing them. Hence, we felt ready, excited, and nervous to meet the globe that controlled it all. We were ready to see the brain.

You can hold a brain in both your hands. It fits there comfortably. It weights about 3 pounds. In other words, it’s about the size and weight of an average cantaloupe. Such an unassuming structure for the burden it carries. It is our brain, in the end, that makes each of us who we are. It shapes our personality, our feelings, and our behavior. Without our brain we simply take up space. We can’t even breathe.

When I held our donor’s brain in my hands, I knew it would be the first and last time I held a human brain. I didn’t hold it for long, but I felt its weight. Its actual weight as gravity pulled down on it, but also the weight of the life it had traveled. Whoever my donor had been in life, it was the brain in my hands that had guided her. Every person has a brain something like the one I was holding. We each have our own globe of cheese, an organ science still doesn’t know much about, that pretty much decides everything in our lives. To think, I was holding the center of human nature in my hands. The feeling isn’t something I’ll forget.