Here's what I mean when I noted that Santana was holding back on "Stone Flower." On the band's next album, Welcome, he included another bossa nova number, and here he cuts loose.
"Yours Is The Light" is an original by two members of the band, keyboardist Tom Kermode and drummer Mike Shrieve. Maybe that let Santana feel he could approach the track with less reverence than he could one by the high priest of the new trend, or maybe it was just that, with "Stone Flower" under his belt, he felt more confident in working his own San Franciscan fire into the Brazilian waters.
Either way, the band is just as bossa-nova cool and airy as you could wish for on this track, with flutes, brushy percussion, and acoustic piano like the trickling of a sylvan spring, and with guest vocalist Flora Purim doing her trademark angel thing on top of it all. But this time, when it all builds up to a guitar break, Santana actually takes one. Rips off a beautiful solo, with all the passion he's known for.
And it's perfectly in-context, too - note how, as singing as it gets, he frequently interrupts his sustain, shuts it all down, to observe the tricky syncopation of the rhythm section. He's not shredding, he's dancing.
But it's definitely cathartic - especially because this is the last track on the first side of the record, and the first time he really cuts loose on the whole album. It's a band album (and a wonderful one), not a guitar-hero one.