"Thank you for your letter. I will try to take your words to heart. There must be something in what you say, because there generally is. But I’ve made another shot at old K. M. last week, reading the Marx-Engels correspondence just published, without making much progress. I prefer Engels of the two. I can see that they invented a certain method of carrying on and a vile manner of writing, both of which their successors have maintained with fidelity. But if you tell me that they discovered a clue to the economic riddle, still I am beaten – I can discover nothing but out-of-date controversialising.To understand my state of mind, however, you have to know that I believe myself to be writing a book on economic theory which will largely revolutionalise – not, I suppose, at once but in the course of the next ten years – the way the world thinks about economic problems. When my new theory has been duly assimilated and mixed with politics and feelings and passions, I can’t predict what the final upshot will be in its effect on action and affairs. But there will be a great change, and, in particular, the Ricardian foundations of Marxism will be knocked away.I can’t expect you, or anyone else, to believe this at the present stage. But for myself I don’t merely hope what I say, – in my own mind I’m quite sure."