The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: An attitude that sees sociocultural changes (in general or in the present situation) as predominantly tending towards a less moral, less constructive, or generally worse state of affairs; particularly, the idea that at some point civilizations and cultures reach a peak after which they must inevitably decline. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.