The Prince

Machiavelli wrote this after losing everything. Tortured and exiled from the Florence he had served for fourteen years, he set down what he had actually watched rulers do rather than what preachers said they ought to do. That gap is the whole book. He is not recommending cruelty so much as reporting that it works, and that a ruler who refuses to use it will be destroyed by someone who will.

It reads as cold because it refuses the usual comforts. Five centuries on, the arguments about fortune, reputation and the uses of fear still land, which is either impressive or depressing depending on the day.