The subject of the article is the concept of a man formed by a Polish philosopher and sociologist Erazm Majewski (1858–1922). A special attention was paid the premises, which as defined by Majewski, enabled a man to cross the borders of the animal world. Anthropological studies conducted by Majewski contributed to a deeper understanding of an exceptional being, i.e. man. Majewski made an attempt to solve the riddle of man from the perspective of both natural history and sociology.