This is an important passage for several reasons: first, Kuhn is again calling attention to scientists as humans. Second, he emphasizes that because scientific communities are so successful at teaching their doctrines, extraordinary science can usually only come from someone outside the field. And finally, Kuhn creates a temporal gap: normal science is routine and happens over a long time, whereas extraordinary science is dramatic and instantaneous—the latter emerges “all at once,” like a sudden flash of inspiration.