Several years ago, when I went abroad on a Guggenheim grant leavened with funds from the Rockefeller Foundation for research assistance, I looked in England for a competent person to help me in something more than a clerical capacity. A young lady, apparently in her early twenties, came to see me about the job. She had a degree in economics from an English university. After I had briefly sketched the work I was proposing to do on Léon Walras, she loftily asked me, ‘Who was Léon Walras? I've never heard of him. He wasn't important, was he?’ The young lady did not get the job, but her question left me shattered and continues to haunt me.

Even at the risk of presenting my problem in a more personal way than is seemly, I must allude to the particular source of my interest in Walras and to the antecedents of my puzzlement about his importance.

It all began with a conversation I had with Henry Schultz at the University of Chicago soon after I arrived at Northwestern University in the closing years of the 1920s.

This was at a time when Schultz was writing his article on ‘Marginal Productivity and the General Pricing Process,’ which was to appear in the Journal of Political Economy in October 1929. That article contained a closing section on ‘Errors and Changes in Walras’ Marginal Productivity Theory'; and so we fell to talking about Léon Walras.