The Great Depression was the direct result, he says, of the breakdown of peace in the first decade of the twentieth century. The international spirit of co-operation that had existed throughout most of the second half of the 19th century evaporated with the European struggles for empire. So when crisis loomed in the late 1920s all the lifeboats were full of holes. Franco-German rivallry, the demise of the British Empire and isolationism in the United States all produced paralysis when leadership was needed most.
When leadership finally did arrive, it came in the form of social democracy and labour market rigidities which put a floor under the markets but extended the depression in ways not dissimilar to Japan in the 1990s.
If you like your economics filled with Keynes and history this is for you. If Friedman or Schumpeter is more to your taste, then this is worth reading just to see what the other side thinks.
Great stuff.