The paper deals with intellectual legacy of Kazan University professor N.A. Vasiliev (June 29, 1880–December 31, 1940), the forerunner of modern non-classical logic. A thinker with a wide range of interests, he worked in poetry, philosophy, ethics, psychology, and history. N.A. Vasiliev's path to imaginary logic is presented, along with the revival of his ideas in the early 1960s and their contemporary development.