On the Shortness of Life is Seneca's best-known work. It offers piercing and profound insights into human nature, and a vision of the good life, summarised in his aphorism, "Life is long, if you know how to use it." Seneca elucidates many of the principles of modern productivity manuals, including the wise valuing of time: "People are frugal in guarding their personal property; but as soon as it comes to squandering time they are most wasteful of the one thing in which it is right to be stingy,"-