A certain amount of British folk-lore was brought back to Greece, according to Plutarch ('De defect. orac.' 2), by the geographer Demetrias of Tarsus about this time. He refers to the cavern of sleeping heroes, so familiar in our mediaeval legends.
The word is said to be derived from the root kâsh, "shine." Some authorities, however, maintain that it came into Sanscrit from the Greek.
'Hist.' III. 112.