What do you think of when you hear the word "genius"? Most of us, I suspect, picture a fellow in a white coat who squints into a microscope, twiddles a knob, and says, "Eureka! I've found the cure for cancer!" More often than not, though, scientific and creative discoveries are the result not of bolts of mental lightning but of long stretches of painfully hard slogging. This unromantic reality is the subject of "Sudden Genius?: The Gradual Path to Creative Breakthroughs," a new book in which the British biographer Andrew Robinson examines key moments in the lives of such giants as Marie Curie, Charles Darwin, Albert Einstein...