Lyric discussion by corich 

I always thought "feed the tree" was a reference to the Larry Niven novel "The Integral Trees" where "feeding the tree" was a reference to death (among other things).

Oggy's more definitive answer gives the same basic meaning, but from a different source.

Came here to say exactly this.

The song has always reminded me of that book, where "feeding the tree" was literally what you did when you died. Circle of life stuff, as the people in that novel depended on the trees for their very existence.

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