Like most children, I used to dream that I was lost in the dark. In a house where I could no longer find my bed. Or, indeed, in a city where I could no longer find my home.

That night in Amsterdam, anything could have scared me and brought back that nightmarish feeling – footsteps, a beast, a nasty dog, or a rat rapidly crossing the pavement and disappearing in the gutter. It would have been enough, I guess, to make the dark itself terrifying. In retrospect, it seems strange that I was not scared. Maybe it was walking, the fact that I had walked all day. My body had turned into a kind of automaton, as happens in a marathon: it was moving by itself, and feeding my mind with endomorphins that kept me happily dreaming. Or, I knew that the night could really turn into a nightmare, and something in me was careful not to let it get out of control.

In any case, it illustrates the situation of the philosopher in Wittgenstein's universe. The philosopher is indeed lost in the city of language:

Our language can be seen as an ancient city: a maze of little streets and squares, of old and new houses, and of houses with additions from various periods; and this surrounded by a multitude of new boroughs with straight regular streets and uniform houses. (Philosophical Investigations, I, §18)

The new boroughs represent the domains of science, chemistry for instance. A new sector of language has been deliberately build for a precise purpose. So the scientist knows where he is: playing with C and H and O, building molecules. He knows what the rules are for assembling signs and how to check whether or not the final formulas refer to something real. However, these boroughs are an extension of our everyday language, which is more intricate. Or at least it does not have these precise rules. The streets do not cross at right angles, they bend insensibly. Of course, most of the time we use the same paths, so we know our way, without thinking about it. However it may happen that we see over the roofs a beautiful bell, or a strange tower. We want to get near it. Then we walk away from our neighborhood. We take streets that we have never used before. We get lost. The bell is still there, pointing to our left. It becomes an obsession. The problem is that we haven't got a map, or “a synoptic view of language,” that would show us how to reach the tower. Some philosophers try to build bridges, elaborate constructions that would bring them straight from their own neighborhood above the maze of the city to the strange tower they look for. It might work on paper, but if we try to walk on the bridge, it falls down immediately. Even the philosophers know it. They usually do not try their own bridges. There is only one solution. We have to walk in the city, and learn our way about. Follow the guide:

In teaching you philosophy I am like a guide showing you how to find your way around London. I have to take you through the city from north to south, from east to west, from Euston to the embankment and from Piccadilly to the Marble Arch. After I have taken you on many journeys through the city, in all sorts of directions, we shall have passed through any given street a number of times – each time traversing the street as part of a different journey. At the end of this you will know London; you will be able to find your way about like a born Londoner. (Gasking and Jackson, 75) 

The difference between the strange tower in the city and the philosophical problem, the point where the metaphor fails, is that if we could find a way to reach the bell, then it would loosen its grip on us. It would lose its beauty and strangeness, crumble down into nonsense, something insignificant. We would look at it and we would not even wonder what could attract us to it. We would know: it was just a grammatical mistake, an optical illusion if you will, a colorless vapor steaming from the canals which had made the tower look bigger, or moonlight turning the common bricks into precious stones they were not.

Philosophical problems, in Wittgenstein's universe, are quite akin to obsessions, or indeed phobias: something that we meet over and over again, that scares us and fascinates us. They obsess the philosophers but they are nonsense. They stem from a wrong assemblage, one word taken for another, or words that connect to each other in a distorted way. Once we have understood that philosophical problems are grammatical mistakes, in this sense, and understood through which undue combinations they were formed, once we have found our way in the city of language, they lose all meaning, and we are free. The charm is over. “Philosophy is a battle against the bewitchment of our intelligence by means of language” (Philosophical Investigations, 109). In this sense, philosophy is a therapy against philosophical problems like obsessions and intellectual torments. It should make philosophical problems

completely disappear. The real discovery is the one that makes me capable of stopping doing philosophy when I want to. The one that gives philosophy peace, so that it is no longer tormented by questions which bring itself in question. (Philosophical Investigations, I, §133)