Lyric discussion by light vessel 

I agree with a lot of what has been said, although about the idea of the band breaking up: this was written for Smile in '67, not for the post-Brian 1970 album that took its title. It is about a break from all the stuff about surfing, but the brief answer, the one that struck me without seeing anyone else's interpretation is this:

It is about death and rebirth.

It is such a sad song, a very sad song, but the "child is the father of man" section lifts it out of the mire and brings rebirth.

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