The paper deals with the specific perception of the tsar Peter the Great’s personality and reforms by Montesquieu. The Petrovian topic is examined through the main writings of the French philosopher (the novel “Persian Letters” and the treatise “The Spirit of Laws”), but also through several secondary texts (the notebooks). The paper seeks to explore the sources of knowledge on Peter the Great and their interpretation. Particular attention is given to the oral sources - the accounts of eyewitnesses which contributed to form a specific negative image of the Russian tsar. It was demonstrated that Montesquieu’s conception of Peter the Great is based on the European tradition of the first half of the XVIIIth-century, but it is largely reinterpreted by the writer who contests the common representations of the tsar like a genius sovereign.