The universe is a joke.
Even before I was shown the meaning of life in a dream at 17 (then promptly forgot it because I thought I smelled pancakes), I knew this to be true--and yet, I have always felt a need to search for the truth, that nebulous, ill-treated creature. Adams has always been, to me, to be a welcome companion in that journey.
Between the search for meaning and the recognition that it's all a joke in poor taste lies Douglas Adams, and, luckily for us, he doesn't seem to mind if you lie there with him. He's a tall guy, but he'll make room.
For all his crazed unpredictability, Adams is a powerful rationalist. His humor comes from his attempts to really think through all the things we take for granted. It turns out it takes little more than a moment's questioning to burst our preconceptions at the seams, yet rarely does this stop us from treating the most ludicrous things as if they were perfectly reasonable.
It is no surprise that famed atheist Richard Dawkins found a friend and ally in Adams. What is surprising is that people often fail to see the rather consistent and reasonable philosophy laid out by Adams' quips and absurdities. His approach is much more personable (and less embittered) than Dawkins', which is why I think of Adams as a better face for rational materialism (which is a polite was of saying 'atheism').
Reading his books, it's not hard to see that Dawkins is tired of arguing with uninformed idiots who can't even recognize when a point has actually been made. Adams' humanism, however, stretched much further than the contention between those who believe, and those who don't.
We see it from his protagonists, who are not elitist intellectuals--they're not even especially bright--but damn it, they're trying. By showing a universe that makes no sense and having his characters constantly question it, Adams is subtly hinting that this is the natural human state, and the fact that we laugh and sympathize shows that it must be true.
It's all a joke, it's all ridiculous. The absurdists might find this depressing, but they're just a bunch of narcissists, anyhow. Demnading the world make sense and give you purpose is rather self centered when it already contains toasted paninis, attractive people in bathing suits, and Euler's Identity. I say let's sit down at the bar with the rabbi, the priest, and the frog and try to get a song going. Or at least recognize that it's okay to laugh at ourselves now and again. It's not the end of the world.
It's just is a joke, but some of us are in on it.