I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it. - Justice Potter Stewart (on hardcore pornography)
In theory, practice and theory are the same. In practice, they are not.
More importantly, I should have realized that “important” is not a binary thing, it’s an analog thing. There are all kinds of different shades of important, and if you try to do everything, you’ll never get anything done.
The difference between a good and a great programmer is knowing when to follow the rules and when to bend them. A good programmer knows the rules of high quality software development and follows them rigidly. A great programmer knows the rules and has deep understanding of the reasoning behind the rules. So he knows when he can safely break them.