<..."The annals of scientific discovery are full of errors that opened new worlds: Bell was working on an apparatus to aid the deaf when he invented the telephone; Edison was tinkering with the telphone when he invented the phonograph. If a man can keep alert and imaginative, an error is a possibility, a chance at something new; to him, wandering and wondering are part of the same process, and he is most mistaken, most in error, whenever he quits exploring."

In this vein, I again highly recommend James Burke's "Connections" series. The book, unfortunately, seems to be out of print, but the program is now available on DVD (much better!).