In 1922, Thomas Edison publicly introduced his latest invention—a new type of money, a commodity-backed currency that he believed was the long-term solution to America's monetary woes. “I want to cast the variable out of money. This gold money is not good enough. It's a fiction” he boldly proclaimed (New York Times 1922).

The stationarity conditions for an autoregressive (AR) process in general are reduced to a remarkably simple inequality if the lag coefficients are restricted to be identical. The condition is not only analytically elegant but also applicable in checking the validity of the stationarity conditions for such a restricted AR process of any order.We are deeply indebted to Professor Paolo Paruolo, NP co-editor of Econometric Theory, and anonymous referees for constructive comments and suggestions that led to significant improvements. Errors, if any, are solely ours.