Sometimes fundamental issues of modern society recur cyclically, such as seismic waves, which spread at regular intervals and shake the earth. Proxy marriage was widely used from the early 1900s to the 1970s, especially in southern Italy. Men who emigrated to the Americas or Australia relied on their mothers, who remained in Italy, to find a "good" wife with whom to create a family. Once married, the wife could join her husband, leave what bound her to this territory to start a new life as a wife.