If you look directly at the Sun, the lens of your eye will focus an image of the Sun on your retina and burn it. There are some photos of ruined eyes at this site:
http://news.bbc.co.uk/2/h...eclipse99/355066.stm
You are not as likely to stare at the sun when it's not eclipsed. But in the crescent part of a partial (nearly total) eclipse, your blink reflex doesn't protect you, since the sky is getting darker and in fact your pupil is opening up! But each piece of the uncovered sun is just as bright as before so it can burn your eye, making a little burned arc. Have you ever caught paper on fire by using a magnifying glass? You don't want to do that to your eye! ONLY TOTAL ECLIPSES ARE SAFE TO SEE WITH YOUR NAKED EYE and ONLY DURING TOTALITY! Be safe, but be sure to go to the one this May if you can, but use safe viewing!
..pat