"Eureka" comes from the story about ArchimedesOfSyracuse. He had to discover the volume of an irregular object - a crown - to determine whether it was made of pure gold or a mixture of gold and lead. The king himself had a personal interest in this matter. The crown had the right weight for the gold, and lead is lighter than gold, so an impure crown would have to be slightly bigger, but how to measure it?
While sitting back in a hot bath, Archimedes noticed some of the water spilling over the side - the bath had been too full. He realized that the volume of the water spilt would be the same as the volume of his body that was spilling it. Eureka! A general way to measure volume (because it is easy to measure water). According to legend, he jumped out of the bath and ran naked down the street shouting in exultation.
PiTheMovie adds that Archimedes, who was feeling pressure to come up with a solution, was driving his wife crazy. She told him to relax by taking a bath. Sounds like support for FortyHourWeek.