..a good book can teach you about the world and about yourself. You learn more than how to read better; you also learn more about life. You become wiser. Not just more knowledgeable - books that provide nothing but information can produce that result. But wiser, in the sense that you are more deeply aware of the great and enduring truths of human life.
In a town like London there are always plenty of not quite certifiable lunatics walking the streets, and they tend to gravitate towards bookshops, because a bookshop is one of the few places where you can hang about for a long time without spending any money.