String theory is based on the simple idea that all the four forces of the universe: gravity, the electromagnetic force and the two nuclear forces, can be viewed, as music.
Because of a friend, life is a little stronger, fuller, more gracious thing for the friend's existence, whether he be near or far. If the friend is close at hand, that is best; but if he is far away he still is there to think of, to wonder about, to hear from, to write to, to share life and experience with, to serve, to honor, to admire, to love.