Agreeable men are those who are interested in everything; men who accomplish things, who finish their tasks, are those who, during a given period of time, interest themselves in one thing only. In America these men are said to possess "single-track minds"' their tenacity and their obsession are sometimes boring, but they succeed, by repeated attacks, in demolishing the obstacles that hinder their progress.

Un Art de Vivre (The Art of Living) (1939) - The Art of Working