"But the fact that different goods cannot be exchanged for each other with equal facility was given only scant attention until now. Yet the obvious differences in the marketability of commodities is a phenomenon of such far-reaching practical importance, the success of the economic activity of producers and merchants depending to a very great extent on a correct understanding of the influences here operative, that science cannot, in the long run, avoid an exact investigation of its nature and causes."
That screams "effective demand" of course. Would it have lead him all the way to a liquidity preference theory of the interest rate? If he didn't find his way there himself, it certainly seems like he would have liked a lot of what Keynes had to say.