Shaking The Tree Lyrics

Lyric discussion by vizenos 

Cover art for Shaking The Tree lyrics by Peter Gabriel

One very important thing, which was a major part of Youssou N'Dour's contribution to this song, is the term, "Souma yergon, sou nou yergon", which means in (I think) Somali, "If we had known, if we had only known!"

Since these words begin the song, and are repeated throughout, it's surprising to me that the lyrics shown above exclude them. Why is that, exactly?