Happy Birthday, Dr. Seuss!

His are the magical books that make kids want to read.

But the man most of us know as Dr. Seuss, Theodor Geisel, didn't start out as a children's author, reports The Early Show National Correspondent Hattie Kauffman. Studying abroad at Oxford University, he was more of a doodler than a student.

And in the army, he made patriotic films and political cartoons, which are now on display at the Geisel library in San Diego.

Dr. Seuss was born on March 2, 2004.

"The wartime cartoons blew my mind the first time I saw them, and we have hundreds of those drawings," says Lynda Corey Claassen.

After the war, the future Dr. Seuss went into advertising -- selling bug spray and motor oil.

Though instantly recognizable, the Seuss creatures never came easily to their creator.

"Drawing is sometimes painful to me, but I will work a drawing over and over until I can get it, not to perfection, but to as good as I am able to do," said Geisel.

Incredibly, his first children's book was rejected by dozens of publishers. One finally took a chance on Dr. Seuss, and children literature changed forever.

"Kids could memorize them long before they could actually read the words themselves," says Charles Cohen, a Seuss collector and biographer. "He actually began to teach kids to read at an ever-earlier age."

Audrey Geisel says the idea for "Horton Hatches the Egg" came when her husband held a drawing of the elephant up against the light of the window "and as he held it with the translucent paper, it was in our star pine out there and he looked at it, looked at the star pine. And at that moment, poor Horton was going to have to sit on the egg … up in a tree."

And every toddler knows Horton stayed to hatch Maizie's egg, because an "elephant is faithful, one hundred percent." It is just an example of the moral lessons found in the pages of Seuss.

"I've never met anybody who says, 'Oh geez, I hate that Dr. Seuss,'" says collector Cohen. "They all perk up. They all get this great look."

His books have been translated into 21 languages. Almost 500 million have been sold. And, they bridge the generation gap.

"[Children] remember the first book and they remember it was Granddad on the first book, that's all working you see," says Audrey Geisel.

Geisel died in 1991. The Seuss spirit, however, is still everywhere in his San Diego home, in the author's extensive collection.

To celebrate the centennial of his birth, on March 2, children are tipping their hats in thanks. A bronze statue will be unveiled in San Diego, and a U.S. postal stamp issued in his honor. His birthday is now the official Read Across America day.

If he could see all the hoopla that's going on to mark the 100 years, Audrey Geisel laughs and says her late husband would say, "You there, you handle it. Thank God I'm dead."