Money doesn’t grow on trees, and although people can make money out of trees, they cannot make trees out of money. This much may seem platitudinous, but it is worth keeping in mind.

What is true of trees is true of the natural world as a whole, including the human beings that are part of it. Nature is real; money is an abstraction. If money seems real that is because our institutions and practices are so deeply premised on beliefs in it. There is an important sense in which those institutionalized beliefs – in crediting it with a certain value – make money real; but it is not real in the way the natural world is real. If a bank goes bust, if a whole economy crashes, the social upheaval that follows may be immense, but life goes on – people will pick themselves up and start again (and some…