Lyric discussion by HuntingBears11 

Cover art for Moonchild lyrics by King Crimson

It's as simple as "malcolmg" said

The Moonchild is the moonshine Istead of imagining a person , you simply have to imagine moonshine in the river, on the willow ect. And the moon is waiting for the sund to rise.

It's a wonderfull way to describe the moon.