Language features in Osmoglasnik of Stevan Mokranjac

The article is devoted to the comparison of the texts of the Russian and Serbian Osmoglasnik. Three editions of the Church Slavonic language exist in Russia in the singing books of different ages: XI to the beginning of XIV century (old istinnorechie), XIV — beginning of the XVII century (razdelnorechie), from 1666 to the present time (new istinnorechie). These three editions are present simultaneously in the Serbian Osmoglasnik recorded an outstanding composer Stevan Mokranjac. This allows the Serbian Osmoglasnik to be «the embodied history» of the Church Siavonic language of the Russian recension. The article reveals the possible reasons for this unusual phenomenon.