Yes - "Astral Traveller" (1970)

Before it got bloated and full of itself--right around the time the punks showed up, more or less--prog was an innovative and often transcendent expression of rock's polar opposites: accessible and inviting melodies coupled with an impressionistic reliance on instrumental virtuosity. But when it worked, as it often did in its '70s heyday...oh!

"Astral Traveller" is from Yes' sophomore album Time and a Word [Atlantic].