Machining Books

“That's all the motorcycle is, a system of concepts worked out in steel. There's no part in it, no shape in it, that is not out of someone's mind [...] I've noticed that people who have never worked with steel have trouble seeing this—that the motorcycle is primarily a mental phenomenon. They associate metal with given shapes—pipes, rods, girders, tools, parts—all of them fixed and inviolable., and think of it as primarily physical. But a person who does machining or foundry work or forger work or welding sees "steel" as having no shape at all. Steel can be any shape you want if you are skilled enough, and any shape but the one you want if you are not. Shapes, like this tappet, are what you arrive at, what you give to the steel. Steel has no more shape than this old pile of dirt on the engine here. These shapes are all of someone's mind. That's important to see. The steel? Hell, even the steel is out of someone's mind. There's no steel in nature. Anyone from the Bronze Age could have told you that. All nature has is a potential for steel. There's nothing else there.”
― Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values