To start with, the mechanism of mythologizing, on the levels of both artistic and mass conscience, returned to its active role in the 20th century, when there appeared the impossibility to explain the world phenomena with the help of rational connections. The active use of mythology is based on the total reconsideration of the public history, and the facts, which were supposed to be truthful before, are now probable to turn into myths. The destruction of one myth usually gives birth to another one. (Vance 1990, p. 18) The first impulse for new mythologizing was given by symbolists. Already at the end of 19th century, pondering over the nature of symbolism as the most significant phenomenon of the new art, Yeats paid attention to the mythological tendency as the real way to return imagination to poetry, thus stimulating its further development by his own creative work. Yeats saw the contribution of Irish literature into modern art in opening new poetic source – Irish myths, which may give the most unforgettable symbols to the new age. He saw the advantage of myths in their close connection with national art, because many images and motives of Celtic myths and ancient epos, having transformed into fairy-tales, have been kept in oral tradition to the 20th century. This connection gave Yeats the feeling of direct connection with the past epoch. The attitude of Yeats to the national folklore and mythology was mostly defined by cultural tasks, which were urgent for Ireland at the end of 19th century, and in solving of which he played one of the principal roles, not only as a poet but as an organizer of literary societies. The main subjects, which Yeats discussed in his works, were nationalism of Ireland, Celtic myths, mysticism and love. But mysticism is for sure the major line of all his creative work.