The exclamation attributed to Archimedes, who is said to have cried out "Eureka! eureka!" (I have found it! I have found it!), upon suddenly discovering a method of finding out how much the gold of King Hiero's crown had been alloyed. Hence, an expression of triumph concerning a discovery.
The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...' Isaac Asimov
Your best ideas, those eureka moments that turn the world upside down, seldom come when you're juggling emails, rushing to meet the 5 P.M. deadline or straining to make your voice heard in a high-stress meeting. They come when you're walking the dog, soaking in the bath or swinging in a hammock. Carl Honore
Creativity and insight almost always involve an experience of acute pattern recognition: the eureka moment in which we perceive the interconnection between disparate concepts or ideas to reveal something new. Jason Silva
There are occasionally eureka moments - off the top of my head, maybe Darth Vader's theme, you know, the imperial march. John Williams