Herbie Hancock's jazz-funk masterpiece, "Actual Proof":

Original version from Thrust (1974):
Actual Proof from Thrust

Live version with Herbie playing acoustic piano from Flood (1975). Same personnel as in Thrust including killer drummer Mike Clark. Totally swinging and tight. Herbie's edgy solo builds in intensity with every chorus til it runs over with testifyin' gospely-funky-post bop-Bartok goodness. I fuckin love this shit:

Actual Proof live version from Flood

Funk band in Michigan doing a decent cover of it. Interesting hearing a sax in the mix.

Actual Proof performed by band "Liquid Street" (2009)