Slavic languages had no distinct script of their own. The early Cyrillic alphabet was a simplification of the Glagolitic alphabet which more closely resembled the Greek alphabet. It has been attributed to Saint Clement of Ohrid , a disciple of Saints Cyril and Methodius.   http://en.wikipedia.org/wiki/Saints_Cyril_and_Methodius       http://www.macedoniainfo.com/cyrill_and_methodius.htm