"Even when I was a little girl, I knew I wanted the whole world to know who I was, to love me and be affected by me."
-- Madonna, to People, May 13, 1985

"Listen, once you pass 35, your age becomes part of the first sentence of anything written."
-- Madonna, to Out magazine, April 2006

"Though I have fears, I think truthfully I'm going to live to be a very old age. If what I've gone through hasn't killed me yet, nothing's going to. That's my [bleeping] opinion."
-- Madonna, to Vogue, October 1996

"So what are you going to do when you get older, Madonna? Are you going to be going on 50 and still get up onstage and shake your booty, like Cher? What happens when your body goes?"

"Then I'll use my mind."
-- From an interview with Madonna, in Vanity Fair, October 1992

Judging by her ever-lean physique, Madonna's body has gone nowhere. Nevertheless, 50 is not the new 30; however, it does mean something different today than it did a few decades ago. Take this defense of the birthday milestone from AARP magazine:

Most of us, at 50 and beyond, are happy with the lines we've earned and the lives we've led. Still, nobody can deny that being a quinquagenarian today is a whole new ball game. Fifty can mean starting a brand-new career or soaring to new heights in an old one (before "Lord of the Rings," few would have recognized the accomplished indie actor Viggo Mortensen).

It can mean having young children (Sharon Stone has three kids under age 7). Or it can mean the freedom and confidence to do whatever the heck you want -- whether it's to spend time with family, write children's books, take to the stage in a corset, or, like Madonna, do all three.

Also turning 50 this year: Former first daughter Caroline Kennedy, actors Kevin Bacon, Alec Baldwin, Michelle Pfeiffer and Sharon Stone, country singer Tanya Tucker, talk show host Ellen DeGeneres, "Sex and the City" author Candace Bushnell and film director Tim Burton.

Happy Birthday, Madonna!