The Joyful Wisdom (German: Die fröhliche Wissenschaft) is a book by Friedrich Nietzsche, first published in 1882 and followed by a second edition, which was published after the completion of Thus Spoke Zarathustra and Beyond Good and Evil, in 1887. This substantial expansion includes a fifth book and an appendix of songs. It was noted by Nietzsche to be "the most personal of all [his] books", and contains the greatest number of poems in any of his published works. In The Joyful Wisdom, Nietzsche experiments with the notion of power but does not advance any systematic theory. The book contains Nietzsche's first consideration of the idea of the eternal recurrence, a concept which would become critical in his next work Thus Spoke Zarathustra and underpins much of the later works.