Hi Joseph glad you enjoyed the lesson and thanks for the kind comments. From my understanding the song was written very quickly by the band. Apparently the album was all done but the record company said that the album was slightly to short in length and was told to add one more song. So the band came up with the chord progression and Gabriel added the works and was recorded and added to the final album very quickly. Kind of sounds like the story behind Smoke on the Water with Deep Purple.