When you finally grasp it, understand that something that’s been confusing you for long, I don’t think you’ll ever find such expressive word to all the joy you get as: Eureka!* It’s exactly what you would want to say. It’s exactly what I subconsciously shouted upon realizing a missing fact.

This tiny, yet powerful, word though has quite a story, I thought I’d share. Hope you enjoy it.
Date of Origin 16th c.
The Greek mathematician Archimedes (c. 287–212 bc) was commissioned by King Hiero II of Syracuse to find out whether the goldsmith who had made a new crown for him had fraudulently mixed some silver in with the gold. In order to do so, Archimedes needed to ascertain the metal’s specific gravity. But how to do this? According to Plutarch (a Greek historian), he decided to take a bath to ponder the problem. He filled the bath too full, as he stepped in it some of the water overflowed – and it suddenly occurred to Archimedes that a pure-gold crown would displace more water if immersed than one made from an alloy. Elated at this piece of lateral thinking, Archimedes is said to have leapt out of the bath shouting heúrēka! * (The goldsmith, incidentally, had adulterated the gold.).
The earliest occurrence of the word in an English text as an exclamation of delight at discovery is in John Dee’s Preface, but there it appears in Greek characters; the first English author to fully naturalize it was probably Henry Fielding in Joseph Andrews 1742; ‘Adams returned overjoyed cring out “Eureka!”’

* Etymology: The word comes from Ancient Greek εὕρηκα heúrēka “I have found (it)”, which is the 1st person singular perfect indicative active of the verb heuriskō “I find”. The reconstructed Ancient Greek pronounciation is [heúrɛːka], while the Modern Greek pronounciation is [ˈevrika].