Yesterday I discussed why "no two snowflakes look alike," but few people will ever try to test this idea as passionately as did a Vermont farmer named Wilson Bentley. Back in 1885, Bentley was the first person to photograph a single crystal of snow. And he devoted much of the rest of his life, at least during the winter, to finding and photographing different snow crystals.

In 1931, Bentley published a book of his photos with help from the U.S. Weather Bureau. The book was titled simply "Snow Crystals," and in it he showed off more than 2000 of his pictures. More than any other event, this book introduced the world to the complexity, beauty and uniqueness of individual snow crystals. That was 70 years ago, so by modern standards, the quality of his images is low, but most experts agree that his photographs remain some of the best ever taken.

Recently, there's even been a children's book written about Wilson Bentley. It's called "Snowflake Bentley," and in 1999 it won the Caldecott medal, an award given each year to a distinguished American picture book for children. You can find out more about Wilson Bentley on the web at, appropriately,

snowflakebentley.com