Music is, in one sense, merely a series of fleeting vibrations that arise and subside. How could it be that something so insubstantial fills us, and calms us, and makes us weep? Because, says W. A. Mathieu, music bridges mind and heart, self and other, and affirms our place in the world. Everyone uses the bridge of music, from casual listeners to devoted professionals. Mathieu's delightful and trenchant prose asks you to question what music is, how it works, and how to understand its value in your life, in the life of your community, and in the evolution of the cosmos.