Learn to see through the abstractions
The most important point in this whole article is this: You need to understand what's going on inside all your abstraction layers. Each abstraction presents an illusion, but the best decisions happen when you can see through the illusion.
[Eric Sink]
A great article, and so is the follow-up. It seems many don't feel the need to learn about the underlying abstractions facilitated by their environments; however, I feel it should be a requirement. As Joel noted in The Law of Leaky Abstractions: All non-trivial abstractions, to some degree, are leaky. Indeed. I personally do not understand how one can operate on many levels of abstractions without the desire to learn more about them; learning is what satiates the intellectual appetite.