Sraffa's Revolution In The History Of Economics

I don't understand this:

"... and Sraffa's obscure, at least to me, Production of Commodities by Means of Commodities." -- Gavin Kennedy

It seems to me that if one is interested in interpretations of Adam Smith, in particular, or the history of economic thought, in general, one is obligated to study Sraffa's impact until his interpretation is no longer totally obscure. If one cannot understand his original works, one can always look at secondary sources.

In old Wikipedia edits to the entry on Classical Economics, I tried to go into changes in how scholars look at the history of economic thought. As usual, I recommend other writers, for example, Roncaglia (2005) or Screpanti and Zamagni (2005). (I'm having trouble reading both these books. The minor variations in textbook variations of ideas with which I am quite familiar doesn't hold my attention. In particular, I have read the first edition of Screpanti and Zamagni and previous contributions by Roncaglia (e.g., 1978a, 1978b, 2000, and 2001).) Screpanti and Zamagni are particularly good on how neoclassical general equilibrium theory has run into a dead end, for internal reasons.

• Alessandro Roncaglia (1978a). Sraffa and the Theory of Prices (Translated by Jan Kregel), John Wiley & Sons
• Alessandro Roncaglia (1978b). "The Sraffian Contribution", in A Guide to Post-Keynesian Economics (edited by Alfred S. Eichner), M. E. Sharpe
• Alessandro Roncaglia (2000). Piero Sraffa: His Life, Thought and Cultural Heritage, Routledge
• Alessandro Roncaglia (2001). "Production of Commodities by Means of Commodities Between Criticism and Reconstruction: The Given Quantities Assumption", in Piero Sraffa's Political Economy: A Centenary Estimate (edited by Terenzio Cozzi and Roberto Marchionatti), Routledge
• Alessandro Roncaglia (2005). The Wealth of Ideas: A History of Economic Thought, Cambridge University Press
• Ernesto Screpanti and Stefano Zamagni (2005). An Outline of the History of Economic Thought (Translated by David Field and Lynn Kirby), Second edition, Oxford University Press