In their contribution, the authors examine the issue of the origin of Slavonic literature, the Old Slavonic language, connected with the important activity of the great Slavic missionaries, Sts. Cyril and Methodius. The formation of the first state of East Slavs coincides with the adoption of Christianity and the confirmation of the word as the divine Logos. In Christian interpretation, the word gains an ontological status of God›s wisdom. The authors examine the development of the word (in terms of the language) by analysing the activities of St. Cyril as the founder of the Kiev letters. Their attention is focused on the analysis of the work of Gregory Skovoroda, Taras Hryhorovich Shevchenko, Lesya Ukrainka and others. Works of these writers show that the word has an archetypal character in Ukrainian culture and its symbolic structure penetrates all stages of its development. The word takes the form of an «apostolic mission», reveals and exposes the soul of the Ukrainian nation. It has Christian origin, and its cultural and historical manifestations strengthen national identity and the nation state.