Very early in our mathematical education—in fact in junior high school or early in high school itself—we are introduced to polynomials. For a seemingly endless amount of time we are drilled, to the point of utter boredom, in factoring them, multiplying them, dividing them, simplifying them. Facility in factoring a quadratic becomes confused with genuine mathematical talent. 

 I. N. Herstein, Topics in Algebra

 The value of a principle is the number of things it will explain. 

 Ralph Waldo Emerson