In 1928, Scottish physician and microbiologist Alexander Fleming went on a two-week vacation. He left a stack of Petri dishes for a bacteria study in his hospital lab in London.
When he returned, he realized the dishes were never placed in an incubator as intended. Mold grew. The dishes were ruined.
Amid the mess, however, he noticed something unusual. A particular kind of mold stopped the bacteria from spreading. He studied the mold further and ultimately discovered the first antibiotic: penicillin.
How would medicine have turned out differently if Fleming did not pay attention? He could have become angry and thrown the unsalvageable dishes straight into the trash.
But he chose to look. His mistake turned out to be a game-changer.