There is a theory which states that if ever anyone discovered exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarrely inexplicable. There is another theory which states that this has already happened.

Douglas Adams’s line comes from his comic science-fiction series The Hitchhiker’s Guide to the Galaxy, which satirizes humanity’s desire for ultimate explanations by treating cosmology as a setup for jokes. Written in the late 1970s and early 1980s (first as a BBC radio series, then adapted into novels), the Guide repeatedly undercuts grand metaphysical questions with absurdity—most famously the quest for “the Answer to the Ultimate Question of Life, the Universe and Everything.” This quotation appears as a mock-philosophical aside in the narrative voice, reflecting Adams’s broader theme: that any supposedly final account of reality is likely to be provisional, and that the universe is stranger than our explanatory frameworks.

The joke hinges on a paradox: if someone ever achieved complete, final understanding of the universe’s purpose, that very completion would trigger the universe’s disappearance—replaced by something even harder to explain. The second “theory” (that this has already happened) implies that reality’s persistent bafflement may be evidence of repeated cycles of explanation and reset. Beneath the humor is a critique of teleological thinking and intellectual hubris: the desire for a single, totalizing meaning is portrayed as both impossible and self-defeating. Adams suggests that mystery is not a temporary gap in knowledge but an enduring feature of existence—and that certainty may be the most unrealistic idea of all.