Thucydides' and Herodotus' comments on a portentous (and unique) Delian earthquake contain the same phrase, but date the event almost 60 years apart and mutually rule out each other's datings. Two additional problems in these passages point to an explanation for the historians' treatment. They are based on the Delphic oracle quoted by Herodotus which promised to , a paradox based on the island's mythical transition from floating to fixed (Pindar), but liable to confusion with its equally well-known aseismicity. Normally (...) meant (1.1). (shrink)