Alexander Fleming — "I did not invent penicillin. Nature did that. I only discovered it by accident."

"The unprepared mind cannot see the outstretched hand of opportunity."

"The power of observation is crucial in scientific research."

"The thought that I might have discovered something which would be of value in treating disease was, of course, uppermost in my mind."

"When I woke up just after dawn on September 28, 1928, I certainly didn't plan to revolutionize all medicine by discovering the world's first antibiotic, or bacteria killer. But I suppose that was exac…"

"I certainly did not plan to revolutionise all medicine by discovering the world's first antibiotic, or killer of bacteria. But I suppose that is exactly what I did."