These famous words, written by , might sound like a cliché. But think about what they actually demand. If you cannot build a thing, you do not really understand it.

It is a harder test than it sounds. Cars, phones, companies, governments. We live with these things and could roughly describe what they do. Now try building one from scratch. All the parts you never had to think about are suddenly yours to figure out.

By the same test, we do not understand ourselves. uncovers a little more each year, but how a brain turns electricity into a thought, a memory, or a sense of being someone is still a genuine mystery. Nobody can build one, so nobody can claim to understand one.

The machines in this journey are loosely modelled on that same brain. They are far simpler, and the resemblance only goes so far. But they are the closest thing we have ever built to a working piece of the puzzle, and taking one apart tells you something about yourself as well.

That is what this journey will try to do, from the ground up.