A man's power and intelligence are limited. He who wants to do everything will never do anything. Only too well do we know those people of uncertain ability who say: "I could be a great musician."..."Business would be easy for me."..."I could surely make success in politics." We may be certain that they will always be amateur musicians, failures in business, and beaten politicians. Napoleon held that the art of war consisted of making oneself strongest at a certain point; in life we must choose a point of attack and concentrate our forces there. The choice of a career must not be left to chance.

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