Classic guitar driven 70s rock. Considered by many to be a precursor to Heavy Metal, Deep Purple is a Hard Rock icon.
The book points out a couple of interesting things about this song. First, that this song is (obviously once you hear them both) an influence on Woman by Wolfmother. Second, that the lyrics were an afterthought, hastily written in a pub. If you read them, they actually scan as a teenagers poem scrawled in red ink on a binder. The music is obviously the draw here. Guitar and bass and organ mirroring each other with great thumping drums keeping time. The organ is a really distinctive sound in such a hard band. There are also some great guitar solos. The lead guitar solo at 1:30 is so clearly a prototypical heavy metal guitar lick, that it is no wonder so many guitar players name Ritchie Blackmore as an influence.