His most recent one is on the discovery of money, where he asks

Do we need to elevate the notion of money from the level of cultural construct, where we created our problems, to the level of universal fundamental, where we might be able to solve them?

and concludes

I think we do, and the first step is to start thinking of money as something yet to be discovered, like the concept of zero, or the idea of Π (or equivalently, circularity). It is not something to be invented.

He then goes delving into philosophical investigations of the nature of money, but I wonder if he might be better served by looking into evolutionary theory. As I noted in a comment to the post, isn’t money in a sense just an abstracted version of the sort of inter-personal accounting that is associated with and required by reciprocity (especially indirect reciprocity) as it has evolved among humans? A bit of googling turns up these papers on the evolution of indirect reciprocity and (in this context) money as an externalization of confidence. (The latter paper is not available in English, unfortunately.) If nothing else they are at least suggestive of a potentially fruitful approach to discovering the true nature of money.