If a big brother is aiming for the highest electoral office in the land, a little brother may often like to be useful. A Robert Kennedy can be a help, a Roger Clinton a headache. Billy Carter brings beer, but Jeb Bush brings Florida. Two thousand years ago, Quintus Tullius Cicero gave his elder brother, Marcus, an unusually frank guide to winning votes—and, on the principle that democracy's brutal essentials have changed little over the centuries, Princeton University Press has now brought out "How to Win an Election," a new Latin-and-English edition of Quintus's guide for the season of Mitt Romney...