My favorite books, to begin with, were science primers. They interested me for several reasons.

For one thing, they were full of amazing facts. I still remember one of them: light traveled at 186,284 miles per second. You never knew when you might be able to slide a sizzler like that into ordinary conversation.

Only, of course, it turns out that the primers were wrong. Recent experiments have succeeded in getting light -- once thought to travel at the absolute upper speed limit in the universe -- to move even faster.

That leads me to the next thing I liked about science primers. Science was an adventure; the answers kept changing. Good science was like a detective story: you kept putting explanations together to fit all the facts. If you weren't sure that your theory was a good one, you found a way to test it. Sooner or later, you could prove most of the bad theories were wrong. The one that remained was right -- at least, until more evidence came along to contradict it.

This quality of science was a combination of confidence and humility. It showed that people could learn things. After all, science eliminated smallpox, it got us to the moon! But implicit in the scientific method is the notion that all of our learning is a little tentative, subject to later revision. It's a reminder not to get too attached to a certain way of looking at things.

That's easier said than done. Most of the great thinkers of science bravely fought the prejudices of the past -- right up until their own theories came under the attack of new evidence. Then these great scientists were positively rigid, clinging dogmatically to their theories until finally a new generation of scientists brushed the old one aside.

I'm paraphrasing, but one of my favorite quotes comes from the late science fiction writer Robert Heinlein: you can have the warm comfort of faith, or the bleak light of reason, but you can't have both.

Recently I've been reading about that fascinating intersection of faith and reason on display in the famous Scopes Monkey Trial, celebrating its 75th anniversary this month. It -- and the antievolutionary stance of Tennessee's Butler Act -- was one of American fundamentalism's first big public stands. They even had a champion in the impressive personage of William Jennings Bryan, three time presidential candidate, and one of the nation's greatest orators.

But under the double threat of that relentless old agnostic, Clarence Darrow, and the withering reportorial contempt of H.L. Mencken, and even though in fact Scopes was convicted of violating the law against the teaching of evolution, fundamentalism was driven underground for at least two generations, from July, 1925 through the first rise of Jerry Falwell.

It was the public library of my childhood that provided me with science primers. It was the same library that then offered me a host of books on world faiths. I've spent many years reading and comparing the ideas of Christian scripture with Confucian texts, the Rig Veda to the Book of Mormon, the Tao te Ching to the Koran, Native American mythology to the teachings of Buddha.

And I've concluded that Heinlein was wrong. You CAN have both. To live without reason is literally madness. But faith, at some level, informs the actions of almost everyone. Like reason, faith sometimes leads us astray for a time. (As Monty Python put it, "No one expects the Spanish Inquisition.")

As it happens, my own scientific ability was not sufficient to carry me through the theoretical astrophysics major I first picked for myself in college. My faith may not get me into Heaven, either.

On the other hand, I've been pretty good about abandoning a host of my pet theories when the evidence made it clear I was wrong. For that, I thank the library, and the deep lessons of science primers.