Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The semantron, also called a xylon is a percussion instrument used in monasteries to summon monks to prayer or at the start of a procession. The semantron is made of a long, well-planed piece of timber, usually heart of maple (but also beech), from 12 feet (3.5 m) and upwards in length, by 1 feet (45 cm) broad, and 9 inches (25 cm) in thickness. Of Levantine and Egyptian origin, its use flourished in the Greece and on Mount Athos before spreading among Eastern Orthodox in what are now Bulgaria, Romania, Moldova, Serbia, Montenegro, Bosnia and Herzegovina and the Republic of Macedonia. It both predates and substitutes for bells (first introduced to the East in 865 by the Venetians, who gave a dozen to Michael III), being used to call worshipers to prayer.