Let me take you to a field, which for 1 or 2 weeks a year is carpeted lilac in the soft light of dawn. We could be in Kashmir, Iran, Morocco or Spain, somewhere with a temperate climate. Underfoot are rows of leafless purple crocuses, their stigmas a fiery blaze of red. When dried these become saffron, the most expensive spice of all. There isn’t much time for the harvest, as the heat of the rising sun will soon wilt the flowers, so farmers must work quickly, plucking each fragile strand by hand.