Bread, cash, dosh, dough, loot, lucre, moolah, readies, the where-withal: call it what you like, money matters. To Christians, the love of it is the root of all evil. To generals, it is the sinews of war; to revolutionaries, the shackles of labour. But what exactly is money? Is it a mountain of silver, as the Spanish conquistadors thought? Or will mere clay tablets and printed paper suffice? How did we