"The Enchiridion" by Epictetus
One-paragraph review: If you believe that human nature is constantly evolving -- that the spark of what makes someone a human being today animates different passions, energies, and predispositions than what formed people living in previous ages, then the words of Epictetus will mean nothing to you. But that would be to your immense loss. The Stoic philosopher taught just a few decades after the life of Christ, and we are fortunate that one of his students recorded the essence of some of his lessons in the Enchiridion. While it is a short collection -- easily read in little more than an hour -- its simple, practical advice makes an awful lot of sense entirely untethered to the time of its writing. Epictetus certainly had no idea he was speaking to a culture saturated with reality television and social media when he wrote, "If a person had delivered up your body to some passer-by, you would certainly be angry. And do you feel no shame in delivering up your own mind to any reviler, to be disconcerted and confounded?" Yet that advice, like so much else in the Enchiridion, is just as sensible today as it was two millennia ago. For anyone whose knowledge of Stoicism is no deeper than a paragraph in a history textbook, reading this book is a worthwhile investment of merely a few minutes.
Verdict: Rewards those who know that human nature is fundamentally unchanging