 The most reliable first-hand account of the activities at the time in Pliska is "An Account of Letters" ("O pismenech"), a treatise on Slavic literacy written in Old Church Slavonic, thought to be composed shortly after 893.The piece calls for the creation of a common Slavic alphabet.In 893, shortly after his rise to power, the new Bulgarian ruler Simeon the Great, summoned an ecclesiastical council in the new capital Preslav, where Clement was ordained bishop of Drembica and Velika.