If we study the Phelps-Brown-Hopkins index and others like it, we find that most inflation in the past eight centuries has happened in four great waves of rising prices.

Cycles must be teased from the data, commonly by statistical inferences in which the evidence is “filtered” and “detrended” by various techniques.

Otherwise, the author has found that price-revolutions in general are (with some exceptions) entirely unknown to most economists, political leaders, social planners, business executives, and individual investors, even as they struggle to deal with one price-revolution in particular.5

The third assignment is consider the consequences of price-movements, or more precisely the consequences of movements that prices represent. These

The fourth wave commenced in the year 1896, and has continued since, with a short intermission in some nations during the 1920s and early 1930s. It is the price-revolution of the twentieth century.

The second task is to explore the question of cause. Braudel himself believed that these great waves were the strongest secular pattern in modern economic history, but he thought that the task of explaining them was the “most neglected” problem in historiography, and “impossible” to solve.

One must learn to look the evidence in the face, without fixed ideological, theoretical or epistemological preconceptions. We are sometimes told that this is impossible. So it is—for some people.9

Today, we are living in the late stages of the price revolution of the twentieth century. Disaster does not necessarily lie ahead for us. This book does not predict the apocalypse. It does not attempt to tell the future. To the contrary, it finds that uncertainty about the future is an inexorable fact of our condition.

The purpose of this inquiry is to stimulate growing interest in this subject, by studying each price-revolution in turn, and then by comparing one with another. We shall describe the four great waves in their most important aspects: first, their timing, magnitude, rhythm, volatility, and the sequence of secular change in price levels; second, the