'The Philosopher's Joke' is a work by Jerome K. Jerome. It’s a humorous novel exploring the concept of immortality. The plot revolves around a philosopher who discovers a potion for immortality and decides to share it with his six friends. The friends are initially excited at the idea of eternal life, but as they start to live forever, they grapple with unforeseen circumstances and challenges, which the philosopher views as a practical joke on his friends.