The Greeks being taught by their Oracles, that their accuſtomed Sacrifices were to be offered κατά τρία, which they underſtood as if their Year were to be regulated by the Sun, and their Days and Months were to be adjuſted by the motion of the Moon; were always ſolicitous, how by certain Periods they might reduce the diſagreeing motions of the Luminaries to a Third ſomething in which they might agree: Hence in the ancient times they are ſaid to have uſed a Biennium, intercalating every other year: But fault was found with this, and 'twas ſucceeded by a Quadriennium; upon the return of which the Olympic Games were celebrated.