Biologically, physiologically, we are not so different from each other; historically, as narratives - we are each of us unique.

It really is a very odd business that all of us, to varying degrees, have music in our heads.

Music can move us to the heights or depths of emotion. It can persuade us to buy something, or remind us of our first date. It can lift us out of depression when nothing else can. It can get us dancing to its beat. But the power of music goes much, much further. Indeed, music occupies more areas of our brain than language does-humans are a musical species.

Music can lift us out of depression or move us to tears - it is a remedy, a tonic, orange juice for the ear. But for many of my neurological patients, music is even more - it can provide access, even when no medication can, to movement, to speech, to life. For them, music is not a luxury, but a necessity.

In examining disease, we gain wisdom about anatomy and physiology and biology. In examining the person with disease, we gain wisdom about life.

Psychotic hallucinations, whether they are visual or vocal, they address you. They accuse you. They seduce you. They humiliate you. They jeer at you. You interact with them.

Music, uniquely among the arts, is both completely abstract and profoundly emotional. It has no power to represent anything particular or external, but it has a unique power to express inner states or feelings. Music can pierce the heart directly; it needs no mediation.