Humor is the only test of gravity, and gravity of humor; for a subject which will not bear raillery is suspicious, and a jest which will not bear serious examination is false wit.
At a dinner party one should eat wisely but not too well, and talk well but not too wisely.
In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted.
You can't just ask customers what they want and then try to give that to them. By the time you get it built, they'll want something new.
It is easier to exclude harmful passions than to rule them, and to deny them admittance than to control them after they have been admitted.
There ain't no free lunches in this country. And don't go spending your whole life commiserating that you got raw deals. You've got to say, 'I think that if I keep working at this and want it bad enough I can have it.'
Truth has beauty, power and necessity.