In a sense, Western markets are like Western medicine: Just as an outbreak of incurable plague would lead to both a renewed search for sound cures and an atavistic appeal to folk remedies, so the Depression stimulated both productive thinking about the sources of business instability as well as destructive appeals to extreme nationalism, protectionism and military aggression.
The whole article is excellent. I'm still pondering this passage. In a plague, medicine drives people to one extreme or the other out of fear: both those who are thinking progressively and those who are appealing to folk remedies do so because they want to stem the plague. Do markets drive people to similar extremes because of fear, or is there a confounding variable in the comparison?