There is a moment, early in a recording by Miles Davis' The Rhythm Section, when the saxophonist seems to quiver a little, as if he were unfamiliar with the music, had lost the ability to read from the sheets, or transpose in his head, or wasn't quite sure where he was. If you guessed all of the above, you'd be right.
Art Pepper, the saxophonist, had forgotten that he was to record in the studio that day; mainly because he was coming off of a heroin high and was not quite sure of the year [it was 1957], the place [it was Los Angeles] or the location of his instrument [it was under the bed in a rather poor state of maintenance.] He managed to get to the studio, though, in some sort of condition; a studio filled with musicians of whom he had heard [everyone knew of Miles Davis by that time], but with whom he had never worked. Since arriving at a studio in rather rough shape is not abnormal in jazz circles, they took it more or less in stride, as long as Pepper could play.
And play he did. While a little rough at first, Art Pepper managed, on that long day in LA, to record one of the seminal works in jazz, "Art Pepper meets The Rhythm Section".
Pepper's life was not easy. He struggled for many years with drug and alcohol addiction, lost out on gigs and chances for fame, went for long periods without employment and, seemingly, without friends. But, talent will out, and he became a clean, sober, and trustworthy studio musician, and then, with no small amount of help from Davis and others, the originator of what's now recognized as the West Coast jazz sound.
If you wish to read more of him, I cannot recommend more strongly his autobiography, Straight Life.
I could speak of him endlessly, but it's best to just listen to what he could do, while imagining yourself driving over the 6th Street bridge in LA in the middle of the night with the top down; or looking out over that sparkling city from Mulholland Drive.