Computers are important--everyone knows that. But computers aren't nearly as important as the ideas behind them. If you want to understand why computer science is important, then you need to read Berlinski's book, The Advent of the Algorithm: The 300-Year Journey from an Idea to the Computer. Berlinski ranks the algorithm as the idea, next to calculus, that has most shaped modern science and, consequently, our world.
If there's one things that gives me pause in recommending this book, it is that I'm not sure how accessible it is to the layman. For someone with a Ph.D. in Computer Science its entertaining and thought provoking and very understandable. I'd appreciate knowing what you think of it.