that's it

"It was good that men should be specialists, I mused. The peculiar knowledge of the pilot and captain sufficed for many thousands of people who knew no more of the sea and navigation than I knew. On the other hand, instead of having to devote my energy to the learning of a multitude of things, I concentrated it upon a few particular things, such as, for instance, the analysis of Poe's place in American literature (...)"
Jack London in The Sea-Wolf.