Ah Ha

That feeling you get when:

Insight! When the grey matter loses the fuzzy grey!
You discover WikiWikiWeb
You find the pattern that solves your problem
You finally understand the cause of a nasty multi-threading bug (note: you haven't found the solution yet, that's the temporary feeling of ImSoGood)
You completely understand what motivated the author to write a pattern
You're dyslexic and about to sneeze
Listening to 80's pop-music (see http://www.aha-fr.com/ and http://www.a-ha.com/)

"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.

"Eureka" translates into English as "I have found it", and is related to the word heuristic.

"No, Eureka is Greek for 'This bath is too hot'." -- DoctorWho

"No, Eureka is Greek for 'I'm naked!'".

Also documented by MartinGardner in Aha! Insight [ISBN 0-71671-017-X ].