# Thomas Sargent's intuition as to why every covariance stationary series has an infinite-order Wold representation

In his classic book "Time Series Analysis", James Hamilton references Thomas Sargent (["Dynamic Macroeconomic Theory"], 1987, pp. 286-290) as a "nice sketch of the intuition behind this result [Wold decomposition]". Can someone explain Sargent's intuition as to why every covariance stationary series has a Wold representation (with an infinite number of parameters)?