THE history of ideas is a strange bird indeed. At times, when the Owl of Minerva flies at night, one can detect a steady progress to human thought, which leads some to go so far as to suggest that such progress will inexorably occur in the future. At other times some philosophers of history or historians of philosophy have noticed either a decline in man's reflective ability to deal with the world around him, or a qualitative neutrality in the thought of different ages when these ages are compared. This neutrality may be seen either as a monotonous succession of one theory after another or as a process wherein each intellectual advance is succeeded by a period of barbarism, leaving us with the same human predicament we started with. What is not often noticed is the intermittent character of the history of ideas. Often an idea is suggested, held to be true for a while, then ignored, finally to be rediscovered. But if the idea is ignored for too long, the rediscoverers may consider themselves discoverers. This is unfortunate for two reasons: (1) It does an injustice to the original discoverers (or creators) of the idea; and (2), it may prejudiciously result in a too narrowly circumscribed treatment of the idea.
In this book I suggest such an intermittent history to the idea