Steven Kates makes some thought-provoking comments, some of which might be read in ways not quite the intended one. a) "aggregate demand failure" is not necessarily the same thing as "over-production" -- presumably a sudden fall in AD, immediately resulting in a corresponding fall in AS, would count as an explanation of the resulting recession? b) to the extent that changes in AS lag those in AD, over-production would be a *consequence* of recession. One could assert both the above without holding that "over-production causes recessions". I don't think Keynes has to be read as making the last claim mentioned, but it would seem that Steven does -- so this is a request for suggestions for further reading. Dr Julian Wells