It's hard to imagine cooking without spice. Basic spices, such as pepper and chilli, and more exotic ones, which, depending on where you're from, can include galangal, cardamom, grains of paradise, Sichuan pepper or caraway, add layers of flavour to food that would otherwise be one-dimensional. Wars have been fought and countries have been colonised in an effort to control the spice trade.

In The Book of Spice, John O'Connell writes, "We take them for granted today, now that they are everywhere and, for the most part, dirt cheap, but spices might just be the most important commodities ever - more important even than oil or gold. For most of human history they have been held in sacred regard, despite the fact that in dietary terms they are utterly inessential.

"No one ever died for want of spices. And yet thousands died in their name - both the plunderers and the plundered. The desire to control the trade in major spices such as nutmeg, cinnamon, cloves and black pepper led Europe's mercantile powers to commit atrocities on a par with those we're currently witnessing in the more turbulent parts of the Middle East."

He points out the early European explorers "discovered" the rest of the world in their search for spices. "All the major expeditions … Christopher Columbus … Vasco da Gama … and Ferdinand Magellan were compelled either wholly or partly by a greedy need to find the places where spices grew so that the traditional middlemen - the Arab and Phoenician traders who sold spices on to merchants in places such as Venice and Constantinople - might be cut out of the picture."

Don't buy the book if you're looking for recipes - there are none. But O'Connell gives interesting information about ingredients we don't give much thought to, other than how they change the flavour of our food. Blue fenugreek, he writes, is "used in Chinese medicine to relieve 'painful swollen testes'"; about black pepper - probably the longest entry in the book - we learn that it's "the second most widely traded spice after chilli peppers" and that it's been used to treat everything from sore throats to erectile dysfunction and menstrual pain. Saffron - known as the world's most expensive spice due to the labour-intensive harvesting (the stigmas in the crocus flower need to be picked by hand) once flourished in England and, O'Connell writes, Cleopatra used to bathe in "saffron-scented mare's milk as a prelude to sex".