U2's first show in Portugal

"The one member of the band who believed we could get somewhere was Adam. He was always talking in terms of record deals, making albums and being on the road. To us that was a joke, but by 1980 we all recognized there was something happening. We didn't understand it for a while. You can call it chemistry, because there is no way to describe what it is when a particular group of musicians is playing together and you get the feeling that there is something special there. There was some kind of spark present when the four of us played together." - The Edge, 1999