 More recently , Glass based the philosophical and musical structure for his Seventh Symphony on the Wirrarika sacred trinity . Glass wrote about the work 's respective movement headings and their relation to the overall structure of the symphony , " ' The Corn ' represents a direct link between Mother Earth and the well @-@ being of human beings .... ' The Sacred Root ' is found in the high deserts of north and central Mexico , and is understood to be the doorway to the world of the Spirit . ' The Blue Deer ' is considered the holder of the Book of Knowledge . Any man or woman who aspires to be a ' Person of Knowledge ' will , through arduous training and effort , have to encounter the Blue Deer .... " 
