It is widely known that Stevens was devoting his time and energy in the pursuit of his family`s genealogy during the 1940s. Although many critics pay attention to the names of his ancestors and of many places in Pennsylvania frequently appearing in his later poems, they fail to disclose how this concern with his past fits into the whole framework of his poetry and thinking. This paper tries to bring to light the fact that his genealogical concern sharpens his sense of the historical reality, on which our lives are embedded in the form of a tradition or a civilization. Stevens, in on poem, illustrates that the past provides "extraordinary references" for ordinary people at the present, which enable them to lead their lives according to what has been "endured and mastered" in the past. He defines the past living in the present as a tradition, and relates it to the young Aeneas carrying his father on his back, to save him from the ruins of the past. Stevens considers a tradition as a supreme fiction, created out of the realities of the past to help people live their lives. He once said that what he was doing in his genealogical study was to "form an agreeable realization of the past." While tracing his own genealogy, he was creating and defining his own tradition out of "the usable past" he inherited from his forefathers. The most meaningful reference Stevens reads out of his 18th century Dutch predecessors` lives is their way of life, which is to live in "an accord with reality". They, whether farmers or religious fanatics, created their own community and culture according to the physical conditions of their land and to the invisible presence of God. He believes that the forms of politico-economic systems or cultural traits of a place spring from the agreement with reality, constituting a true "mythology of a region." Stevens believes poetic images are at the center of a mythology, and says they must reflect the reality of that region. "Imago" tells us the fact that as time goes by, these images form "imagoes" in the minds of the residents to give them a shared identity, and become vehicles to transmit a culture from generation to generation. The period Stevens was preoccupied with his genealogical study coincides with the period he had "a magnificent fury" over poetry and poetics. Out of his genealogical search he has realized that "the agreement with reality" lies at the base of poetic imagination creating a supreme fiction, which is nothing other than "a mythology of a region," or "the ultimate good sense we term civilization".