It is just the same with the music of life, which is called mysticism. Although it can be studied it is of no use unless there is practice also. What is more, if a person asks, "Suppose I play and practice with a book, can I become a great singer?", he would have to be told that he needs a teacher to show him how to use his voice, how to make music. If you have a teacher you can accomplish in ten years what you could never learn alone, by yourself, in a hundred years. That is the purpose for which the guru is intended.