World riddle

The term "world riddle" or "world-riddle" has been associated, for over 100 years, with Friedrich Nietzsche (who mentioned Welträthsel in several of his writings) and with the biologist-philosopher Ernst Haeckel, who, as a professor of zoology at the University of Jena, wrote the book Die Welträthsel in 1895–1899, in modern spelling Die Welträtsel (German; "The World-riddles"), with the English version published under the title The Riddle of the Universe, 1901.

The question and answer of the World Riddle has also been examined as an inspiration or allegorical meaning within some musical compositions, such as the unresolved harmonic progression at the end of Also sprach Zarathustra (1896) by composer Richard Strauss.

Emil du Bois-Reymond used the term "World Riddle" in 1880 for seven great questions of science, such as the ultimate nature of matter and the origin of simple sensations.

In his book Pragmatism (1907) he satirized the world-riddle as follows: All the great single-word answers to the world's riddle, such as God, the One, Reason, Law, Spirit, Matter, Nature, Polarity, the Dialectic Process, the Idea, the Self, the Oversoul, draw the admiration that men have lavished on them from this oracular role.

By amateurs in philosophy and professionals alike, the universe is represented as a queer sort of petrified sphinx whose appeal to man consists in a monotonous challenge to his divining powers.