The Palladium of Rome. It was the sacred buckler which Numa said fell from heaven. To prevent its being stolen, he caused eleven others to be made precisely like it, and confided them to twelve priests called Salii, who bore them in procession through the city every year at the beginning of March.
Idque ancile vocat, quod ab omni parte recisum est, Quemque notes oculis, angulus omnis abest.
Ovid: Fasti, iii. 377.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894