‘Devilry, Unknown and Cross Power’ is a work by folklorist and ethnographer Sergey Vasilyevich Maksimov (1831-1901), completed and published after the author’s death in 1903. He worked in the ‘Ethnographical Bureau’ of Prince V. N. Tenishev, the main aim of which was collecting facts; his employees were to escape ‘any considerations and smartness’. Some of materials were collected by the Bureau personnel, and the final editing of the publication of the data belonged to A. A. Yablonovsky.

As it was stated in the title, the work consisted of three parts, and each of them was devoted to certain folk ideas about mystical forces: devilry, unknown, and cross powers. The ‘impure forces’ included, for example, small devils. The author describes folk beliefs on the favorite places of such forces, their transformations, seducing women, abduction of children, various temptations, devilish obsessions, sayings and prayers to protect people against them. The author mentions such evil creatures as Domovoy (house spirit), bath dwellers, Kikimora, Rusalka, etc. Beside sorcerers and witches, there are people of special occupations connected with impure forces – they are carpenters and stove-makers and shepherds. The ‘unknown forces’ included natural elements and non-material, but influential phenomena; the author mentioned ‘tsar-fire’, ‘water-queen’, and ‘mother wet soil’, as especially important ones. Sacred groves also belonged to the ‘unknown powers’. The largest section of the book was entitled ‘Cross power’; it was not completed by the author, and V. N. Tenishev prepared the text for the publication after the death of the author. It included description of numerous festivals, located mainly in the calendar order: from the Christmas time and the Nativity of Christ to the ‘Nikol'shchina’. And although the holidays were described with varying degrees of details; but each one contained characteristics of ceremonies and performances.

The author repeatedly stressed the complex nature of popular religiosity, where traditional beliefs were intertwined with Christian ones. Despite the literary style of the work, it was a rich collection of factual materials on popular beliefs.