A witty, provocative, story-filled inquiry into the indispensable virtue of loyalty--a tricky ideal that gets tangled and compromised when loyalties collide (as they inevitably do), but a virtue the author, a prizewinning columnist for The Wall Street Journal , says is as essential as it is impossible. Felten illustrates the push and pull of loyalties-- from the ancient Greeks to Facebook--with stories and scenarios in which conflicting would-be moral...