Fully understanding an average program requires an almost limitless capacity to absorb details and an equal capacity to comprehend them all at the same time. The way you focus your intelligence is more important than how much intelligence you have.
At the 1972 Turing Award lecture, Edsger Dijkstra delivered a paper titled "The Humble Programmer." He argued that most of programming is an attempt to compensate for the strictly limited size of our skulls. The people who are best at programming are the people who realize how small their brains are. They are humble. The people who are the worst at programming are the people who refuse to accept the fact that their brains aren't equal to the task.
The purpose of many good programming practices is to reduce the load on your gray cells. You might think that the high road would be to develop better mental abilities so you wouldn't need these programming crutches. You might think that a programmer who uses mental crutches is taking the low road. Empirically, however, it's been shown that humble programmers who compensate for their fallibilities write code that's easier for themselves and others to understand and that has fewer errors.
-- Jeff Atwood, Coding Horror