The Law of Leaky Abstractions

Joel tells us about The law of leaky abstractions. Which means that whenever somebody comes up with a wizzy new code-generation tool that is supposed to make us all ever-so-efficient, people say: "learn how to do it manually first". Code generation tools which pretend to abstract out something, like all abstractions, leak, and the only way to deal with the leaks is to understand how the abstractions work and what they are abstracting away.