The book by M. I. Popov ‘Description of Ancient Slavic Pagan Fables...’ was a mythological lexicon. In the pre-notification, the author wrote about the sources of his work: ‘I chose the matter that constituted the book from different books that I had or could find for reading’. He sought to give his work a scientific appearance, as evidenced by internal footnotes and notes, as well as valuable observations and comments. For example, he criticized the explanation of the name of the river Volkhov, given by the chronicler: the princely son Magus "in the form of a crocodile swam along the river, nicknamed him as the Magus and devoured people." Popov, in full accordance with the tradition of rationalization of mythology popular in his time, explained the origin of the name of the river as follows: Magus robbed on the river, and "in the hands of this he could be seen very skillfully and removed, and therefore became a sorcerer." He sought to give his work a scholarly form; it is obvious at the internal footnotes and notes, as well as valuable observations and comments. For instance, he criticized the explanation of the name of the river Volkhov, given by the chronicler: the princely son Volkhv (Magus) ‘in the shape of a crocodile swam along the river, named Volkhov after him and devoured people’. Popov, in full accordance with the tradition of rationalization the mythology popular in his time, explained the origin of the name of the river as follows: Volkhv robbed people on the river, and ‘and he was rather skillful in it, and therefore he was taken for a sorcerer’. The author cautiously criticized Lomonosov, who thought that ‘it was as if the name of God (‘Bog’ in Slavic – and the river Bug) and the Almighty Creator were given the name’.

Drawing from the previous authors the name ‘Chernobog’ (Black God), P. compared it with the ‘Persian Arimaniy’, considering him the Slavic god of evil. He thought it necessary to have such a god in the Slavic pantheon, probably, for the complete corresponding with the known mythological systems of classical tradition, where evil forces had been personified in the images of gods. He was indignant: ‘Some German publisher of the ‘Short Fabulous Dictionary’ wanted to assign even that bad god of us, calling it Cernebukh. He writes that was how the vandals called the evil spirit, whom they made sacrifices to repulse his wrath’. The author emphasized that although initially it was an evil god and was venerated by Varangians, Slavs also ‘offered him a bloody, sad prayer, as well as a terrible spell’.