Towards the end of the last millennium, when the year 2000 was near, many people were asked what was in their view the most important invention of those thousand years. The majority gave answers like the television, or the computer, or the internet. The Italian philosopher Umberto Eco answered: the cultivation of the bean, whose introduction in the Middle Ages freed the European peoples from the spectre of hunger. In an essay translated and published in the English newspaper The Guardian, he argued in favour of the "humble bean", this highly-proteic, wholesomely-nutritious vegetable. He explained how it's easy to...