Understanding © Eric R. Pianka The difference between knowledge and understanding is subtle but important. A course in auto mechanics might have taught you how a car works and how to repair it, but you would not know how to design one from first principles. Building a car from scratch requires engineering ability, understanding exactly how a complex internal combustion engine works, such as how the camshaft opens and closes intake and exhaust valves in synchrony with pistons moved up and down by the crankshaft, as well as access to high-tech tools and a machine shop, among other things. Last updated 12 September 2014 by Eric R. Pianka