anniversary of its first recording back in 1938, and jeffrey brown joined composer and musician rob kapilowtly at the signature theater in arlington, virginia to look at why the song endures. >> reporter: "over the rainbow." everybody knows this song. but why? what makes us know this song? >> amazingly, the answer to that starts with the very first two notes. in this famous opening idea, there's really only two ideas. one of them i call leap. the other one i call circle and yearn. it's important. >> brown: leap and circle and yearn. >> it's important you learn these technical terms. >> brown: i didn't start off with that in piano class. >> erin: we start off with the big leap. producers were worried nobody would buy the song because of the leap. it's a big leap musically, between two different worlds and two parts of the voice. the first note is low. it's dorothy's troubled reality. it's kansas, aridity, no flowers, it's the black and white of the beginning of the film. >> a place where there isn't any trouble. do you think there is such a place, toto? >> so this is kansas. the upper note i