A methodology of historical or higher criticism and of stylometry/stylochronometry known from Biblical and literary studies is applied to the examination of Nicolaus Copernicus’s writings. In particular, his early work Commentariolus is compared at the level of the Latin language with his later ones (Meditata, Letter against Werner and De revolutionibus) as well as the texts of some other authors. A number of striking stylistic dissimilarities between these works have been identified and interpreted in the light of stylometry/stylochronometry, historical criticism and the history of Copernican research. The conducted research allowed to draw some plausible conclusions about the Sitz im Leben (historical context), the dating of Commentariolus and related matters.