Eureka! When you suddenly understand something, have a brilliant idea, or come up with a solution for a problem, you can shout 'eureka!' (pronounced yoo-reek-ah). When you do so, you are using classical Greek. Eureka translates as 'I have found [it]'. The story behind this expression, whether true or not, is very ancient. Archimedes (287BC-212BC), a scientist who lived in the Greek colony of Sicily, was given a problem to solve by his country's ruler, Hiero. Hiero did not trust a craftsman who had made a gold crown. He asked Archimedes if there was any way to find out if the crown was pure gold without damaging it. Archimedes, who was thinking about the problem while having a bath, noticed that displaced water was flowing over the sides of the tub and shouted: 'Eureka!' A crown of pure gold will displace slightly less water than one which contains cheaper metal such as silver. Hiero's crown failed the test and the craftsman was punished. Experts say Greek crowns, mainly styled with gold leaves, would not have weighed enough for the technique to work. Nevertheless, Archimedes' contribution to science was greater than this example, and he is best known for his work on levers. Sadly, he was killed by a Roman soldier while solving a mathematical problem.