On cycles A cycle means a repetitive pattern with a reasonably recognizable periodicity, and should not be confused with a random walk. I had cause (long ago) to look at data for C19 Britain. My memory is that the early C19 did not show recognizable cycles - variations, of course, good and bad times, financial crises, etc., but no recognizable periodicity. Writers of the time did not write about cycles not because they failed to notice them, but because there weren't any to recognize. By contrast, the second half of the C19, for Britain (but not necessarily other places) had very visible 7-10 year cycles, which really jump out at you from all sorts of data series, and must have been obvious at the time. Hence, late C19 economists in Britain (which dominated the subject at the time) treated trade cycles as an important topic. For the C20 (at least after 1914) cycles are much less clear. The first half was dominated by 2 wars and the great depression of the 1930s. The second half had a quite different pattern, with shorter and more variable cycles (if they were properly called cycles at all), plus one-off events like the oil crisis. Government policy almost certainly played a much more important role, so what cycles there have been in the later C20 are probably different animals from C19 cycles. Without late C19 Britain, we might perhaps not have a recognized topic of trade cycles. Actually, the clear cycles of late C19 Britain are less straightforward than they look, since home and foreign investment followed out-of-step 20(ish) year cycles, with successive cycle peaks dominated by home and by foreign investment. Tony Brewer