The article represents the experience of philological research of the translation of the Vita of St. John Climacus, performed by St. Paisius Velichkovsky. The material for analysis was the translator’s draft autograph – manuscript No. 285 from the collection of the Neamt Monastery. The sources of the translation have been identified: this is a Greek-Latin edition (Paris, 1633), a Russian edition (M., 1647), a manuscript of an early Greek version, a manuscript of a Serbian translation and a Slavic manuscript of a translation unknown to me. The functional load of 14 marginalia of the manuscript is described. A textual analysis was carried out, which showed the absence of omissions, 4 inversions and 26 insertions, among which the vast majority are demonstrative pronouns. A hypothesis has been put forward that, following the word-by-word principle of translation, St. Paisius translated Greek articles with demonstrative pronouns. Examples are given that show the main distinctive feature of the translation of the St. Paisius – literal adherence to the structure of the translated text. There have been cases when a translator discovers hidden meanings in lexemes that require special theological knowledge. I identified 9 lexemes that are missing in the dictionaries of the Church Slavonic language. Examples are given of borrowing translation solutions from St. Paisius by the authors of later translations of the Vita of St. John Climacus: D.R. Ulyaninsky, Saint Ignatius Brianchaninov, P.S. Delitsyn and Optina elders.