This article under takes the first philological analysis of the early diaries and notebooks of V. I. Vernadsky, in particular the 1886 notebook with records of his research trip to Finland. In connection with his work at the Mineralogical Cabinet of St. Petersburg University, Vernadsky participated in expeditions organized by the Society of Naturalists to study deposits of marble. The notebook includes Vernadsky’s ideas about the geological origins of marble. His private correspondence with N. E. Staritskaia reveals the creative individuality of the young scientist.