Although there are other heresies in The General Theory, along with puzzles, opacities, loose ends, confusions, errors, exaggerations, and anachronisms galore, they do not detract from the book's relevance to our present troubles. Economists may have forgotten The General Theory and moved on, but economics has not outgrown it, or the informal mode of argument that it exemplifies, which can illuminate nooks and crannies that are closed to mathematics. Keynes's masterpiece is many things, but "outdated" it is not.

How I Became a Keynesian (2009)