Improvising live is continually searching for something. The musician's changes in tone within a song are precisely the sign of this search. A song is like a concentrated life: it experiments, it changes, depending on what you have found and what you want to find. Rationality is turned off and one can truly communicate. Life becomes music, the mind wanders freely at lightning speed, searching for something. Duane Allman found this thing. He has it at the beginning of the concert and damn, he doesn't let it go until the end.
"He knew exactly where he was going" (Gregg Allman)