Sraffa's research may be divided in two apparently disjointed parts. Therst part is the one where his research interests are closely related withmonetary and banking theory (Sraffa, 1920, 1922, 1932). The second part is the one concerned with the measurement and distribution of the physical surplus produced by an economy (Sraffa, 1925, 1926, 1951, 1960).

There are two objectives in this paper. The first objective is to show that the two parts are coherent with Sraa'sview that the production prices are not determined by the \natural or me-chanical" economic forces alone. A well know quote on this is directly takenfrom Sraa' book:

"The rate of profits [. . . ] is accordingly susceptible of beingdetermined from outside the system of production, in particularby the level of the money rate of interest" (Sraffa, 1960, p.33)".

If the money rate of interest may determine the commodities rate of profits and the commodities rate of profits determine the distribution of the surplus, it must also be the case that the forces that determine the monetary interest rate determine distribution as well. This was an important point already put forward in Sraffa (1922) and subsequently in his debate with Hayek (Sraffa, 1932). Chapter 17 (The Essential Properties of Interest andMoney) in Keynes (1936)' General Theory may be interpreted as addressing this problem using also the arguments put forward by Sraffa. Keynes'himself in the footnote on the own rate of interest at page 223 acknowledged Sraffa (1932) contribution.

The second objective of the paper, expanding and extending Zambelli(2018), is to introduce money, credit and debt inside Sraffian schemes. Using the words of Nuti (1971, p.35) reported in the introduction of Panico (1988a,p.7) this is done because "The most appropriate way of approaching the theory of distribu-tion, reintroducing the reality of class struggle into this importantbranch of Political Economy, seems therefore that of combiningthe Sraan relation between wage and prot rates with the littlewe know - not least from Marx- about the interaction of real and monetary phenomena."

The original contribution of the paper is the inclusion of credit and debtinside Sraffian schemes. This is done without the assumption of the 'long-run' position, where the rates of prots are assumed to be uniform, andwithout the assumption of self-replacing. In order to be able to elucidatethe causal relations between the money rate of interest and the profit rate a rigorous formal treatment of money in within the Sraffian schemes is an analytical necessity that we hope to fullfil.

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References

Keynes, J. M. (1936). The General Theory of Employment, Interest, andMoney. London: Macmillan.

Nuti, D. M. (1971). "vulgar economy" in the theory of income distribution.Science & Society 35 (1), 27{33.

Panico, C. (1988a). Interest and Profit in the Theories of Value and Distribution.

Panico, C. (1988b). Sraffa on money and banking. Cambridge Journal of Economics 12 (1), 7{28.

Sraffa, P. (1920). L'inazione monetaria in Italia prima e dopo la guerra.

Sraffa, P. (1922). The bank crisis in italy. The Economic Journal 32 (126),178{197.

Sraffa, P. (1925). Sulle relazioni tra costo e quantita prodotta. Annali diEconomia II, 277{328.

Sraffa, P. (1926). Law of returns under competitive conditions. EconomicJournal 36 (144), 535{550.

Sraffa, P. (1932). Dr. Hayek on money and capital. The Economic Jour-nal 42 (165), 42{53.

Sraffa, P. (1951). Works and Correspondence of David Ricardo, Vols I-X,1951-1955, and Vol. XI (index), 1973, Cambridge,. Cambridge UniversityPress.

Sraffa, P. (1960). Production of Commodities by Means of Commodities.Cambridge: Cambridge University Press.

Zambelli, S. (2018). Production of Commodities by Means of Commoditiesand non-uniform rates of prots. Metroeconomica 69, 791{818.3