The polio vaccine.
Plymouth Rock.
The earth is round.
A list of great human discoveries would not be complete without, perhaps, the most important of all.
NEVER use the regular cashiers at Walgreen's. Go directly to the cosmetics counter. Cue the heavenly muzak. Yes, yelpers, I NEVER wait for my Snore Strips, Snicker bars or Burt's Bee's Lip Balm. I grab and buy. Otherwise you're behind the lady with the coupons. And she's still cuttin them out. Or the five pimple faced teenagers. All paying separately. Or, the worst, someone who apparently is stocking their bomb shelter and has two carts full of crap.
NEVER. Just go to the cosmetics counter. Tell 'em Thomas S. sent ya!