If he had been a great and wise philosopher... he would now have comprehended that Work consists of whatever a body is obliged to do, and that Play consists of whatever a body is not obliged to do. And this would help him to understand why constructing artificial flowers or performing on a tread-mill is work, while rolling ten-pins or climbing Mont Blanc is only amusement.

— from The Adventures of Tom Sawyer by Mark Twain —

The point of all this is not the reduction of the familiar to the unfamiliar... but the extension of the familiar to cover many more cases.

— from Categories for the Working Mathematician by Saunders MacLane —

Of these three approaches, the last is in many ways the least satisfactory; it is, however, the one that we shall for the most part take.

— from "Lecture 9" of Representation Theory: A First Course by William Fulton and Joe Harris —