This contribution is an attempt to evaluate the impact of the works of Léon Walras on the development of the economic theory of Italian author Piero Sraffa, and in particular on his book Production of Commodities by Means of Commodities (PCC). It could not have been written fifteen years earlier. As a matter of fact, Sraffa's publications and, in particular PCC, do not contain any direct or explicit reference to the work of Léon Walras. However, after Trinity College has opened the Sraffa Archives (SA), the Wren Library of Cambridge University made it possible for researchers to also access Sraffa's manuscripts and private library. These archives are extraordinarily rich and reveal much about Sraffa's life and work. Given this, it seemed interesting – for the occasion of this book dedicated to Pascal Bridel – to search the SA and Sraffa's private library for traces of any influence that Léon Walras might have had on his economic work and how he interpreted Walras's work.

Before presenting the results of our research, it is necessary to elaborate, in a first section, on its purpose: why was there reason to believe that Léon Walras could have influenced Sraffa's critique of marginalist economic theory as well as the elaboration of PCC? To answer this question, we have to go back in time, to the period 1960 to 1980 during which the first reactions to Sraffa's Prelude to a Critique of Economic Theory emerged.