As old problems are conquered, we expect to turn up new problems. A discipline lives on its unsolvved problems; and so, for better or worse, economic… - Paul Samuelson

Needless to say, the partial equilibrium assumptions involved in the domestic demand schedules and the neglect of aggregative relations constitute a serious defect of such a model except as a rough first approximation to the answers in especially favorable cases. Good economic theory will recognize these limitations rather than be predisposed to neglect them.

I had a great admiration for Pigou. I thought that, in many ways, he was not only a faithful follower of Alfred Marshall, but he was also a more fertile developer of the Marshallian tradition than Marshall himself. … Whitehead said to me:“Don’t you think that Pigou was an overrated economist? Wasn’t Foxwell a better man?” Since I am an honest man, I said to Whitehead:“No, I think Pigou was a much more important economist than Foxwell.”

The stock market has forecast nine of the last five recessions.