I was recently invited to write an essay for a promising new web site that launches today, called Being Human. It's all about what it means to be Homo sapiens, and I chose to focus on our brain, which is so fundamental to our unique place in the natural world. In fact, we like to think of ourselves as our brains. You could, after all, imagine yourself as just a brain in a vat. It might be hard to manage, but if someone could figure out the right liquids to put in the tank and the right wires to stick into it, it "ought" to work. Hence, The Matrix. This is actually a new notion, and in my essay, I take a look at our ideas about the brain over the past couple thousand years. Check it out.