Division of the past into convenient "periods" reflects more expediency than reality. Although pivotal events may be chosen to demarcate phases of historical or literary activity, the divisions tend to obscure the actual gradations and overlapping that occur. The decade of the 1920's--particularly in the United States--came closer to having a sharply defined uniqueness than most recognized periods. World War I inflicted a mortal blow upon the comfortable old world of European culture. The stock market crash in October, 1929, extinguished forever the bright lights and levity of the twenties. In the grim darkness of the Great Depression that followed, nothing survived of the madcap period except memories that took on an almost legendary aura.