From JewishExponent.com > Media Clippings > Dream On!:

"As a child, [Alexander] Fleming was a smart student but had a dreamy demeanor and failed to exert himself. As an adult, he worked under a mentor who insisted on sticking to orderly procedures. One day Fleming glanced at a discarded petri dish of bacteria -- which had become contaminated with mold -- and noticed that bacteria near the mold were no longer reproducing. As we now know, Fleming's distracted curiosity led to a scientific breakthrough [penicillin] that helped save millions of lives."