A one-eyed people of Scythia, who adorned their hair with gold. They were constantly at war with the gryphons who guarded the gold mines.
As when a gryphon, through the wilderness ... Pursues the Arimaspian, who by stealth Had from his wakeful custody purloined The guarded gold.
Milton: Paradise Lost, ii. 943.6)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894