I think the first economist must have been named Horatio. He’s the one who had to be reminded there were more things in heaven and earth than dreamt of in his model.

I try to keep my horizons wide by regularly consulting my second-favourite website, The Conversation (with academics who know a lot of interesting things about a lot of topics), to which I’m indebted for most of what follows.

Illustration: Simon Letch Credit:

We’re meant to know all about photosynthesis, but did you realise it means that, “with a bit of sun, a tree uses the natural miracle of photosynthesis to combine a little water with carbon dioxide from the air to produce the building blocks for its own growth, as well as oxygen,” according to Associate Professor Cris Brack, of forest measurement and management at the Australian National University?

So, to oversimplify a little, we breathe in oxygen and breathe out carbon dioxide, whereas trees breathe in carbon dioxide and breathe out oxygen – making them useful things to have around when we have a problem with excess carbon emissions.