To live happily is something everyone has in their own hands, said Marcus Tullius Cicero, the Roman politician, rhetorician, and philosopher. He repeatedly dedicated himself to the core question of our existence: What is the nature of humanity and what gives life meaning and value? His thoughts revolve around inner freedom, the significance of moral norms, the value of friendship, humanity, fate, and pain. This selection from Cicero's letters and philosophical works forms a guide to a good and successful life.