There are plenty of books that I, for one reason or another, lug around as I move about. The complete Hitchikers Guide is one of them and the oldest of the lot. I was given the book in the fifth grade by a teacher who I now realize (with the aid of a decade and a half to reflect upon his impact) was probably one of of the key individuals who forged the man to walks the world today. I was initially turned off by the sheer size of the tome as it was easily longer than any of my textbooks at the time. Hell, it's still longer than most of them in College! I eventually did read the book of course and it is almost certainly my favorite attempt at humor in the history of everything I've examined (which, on the balance, really doesn't say much I suppose).
Flatland is another, though it is thankfully brief. When it was assigned as reading in Calculus, I was delighted as I had already read the novel. I never really liked math until I started to understand that mathematics was simply a language one could use to describe just about anything. Flatland certainly has helped on the journey that continues to this day and builds as a result of a simple narrative a case for hyper-dimensional geometry (like a four dimensional object for example). When I reached the end, I realized that even though I could not conceive of a hyper cube in my mind, the argument that one could model it mathematically seemed iron clad by the end. Better still, for those who played Deus Ex, they might recall that Anna Navarra's kill-phrase was "Flatlander Woman". If you read the book (particularly the chapter specifically regarding women) you realize just how descriptive this kill phrase actually is!
Of all the Rand Novels, the only one I still drag around the country is, unfortunately, the heaviest: Atlas Shrugged. While the book has a number of absolutely damning flaws, I can at least respect the notion of the objectivist hero as something worthy of discussion and even emulation in some respects. Even if the applicable lesson I applied to my own life was "to hell with what other people think".
The most recent addition is probably the most exciting yet; Godel, Escher, Bach: an Eternal Golden Braid. It too is a hefty tome, but more than the rest the book was a terrible slog to get though. The tagline of the book might offer some insight: "A metaphorical fugue on minds and machines in the spirit of Lewis Carroll". At the most basic level, the book simply explores the impact of a self-referential system. This could be in the work of Bach, known for his Cannons (a thing I never even realized was a thing until I read the book and then listened to his music again), or perhaps a simple problem of recursion. The book seemingly wanders about with in depth examinations of so called "Strange loops", amusing dialogues that often feature Achilles and Mr. T (really!), mathematical proofs and computer science theory. It is a book of the best sort. For every discovery it offered it turned up a dozen questions. For every nagging problem that seems doomed to eat away at my my spare time it offers an even more interesting observation.
The thing is, I don't know what I'd call the book in terms of classification. Mathematics, religion, computer science, philosophy, humor - it covers just about every term you'll find in a book store. From the Author's Forward:
"In a word, GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle? What is an "I" and why are such things found (at least so far) only in association with, as poet Russell Edson once wonderfully phrased it, 'teetering bulbs of dread and dream" == that is, only in association with certain kinds of gooey lumps encased in hard protective shells mounted atop mobile pedestals ant roam the world on pairs of slightly fuzzy, jointed stilts?"
Each of these books has, in some fashion, had an impact on my life and the way I view the world. These books might not have that power for every reader of course and each of them requires a commitment of sorts.