The Theory of Pure Capital by F.A. Hayek

Appearing at the height of the Keynesian revolution, this treatise (a 1941 publication) was sadly overlooked. Today it can be appreciated anew.

Hayek’s stated objective was to make capital theory—which had previously been devoted almost entirely to the explanation of interest rates—“useful for the analysis of the monetary phenomena of the real world.”

Hayek reports that he never felt that he had fully completed the book but at 480 pages, it remains the most complete treatise on the subject ever published.
To be sure, this is for serious students, but the effort to grapple with Hayek's thought is heavily rewarded here.