But though the book omits this, it gradually makes clear what the thing is about creating ideal societies: they have to be designed as precision objects, they cannot just (pace Morris) be left to happen by themselves. To design and rule a Utopia, you must be a serious control freak. You must know exactly where everyone is, how many there are, what they are doing, where they are going, and how. The city therefore becomes a machine for life, work, and surveillance. That is why they take the forms they do -- usually grid-pattern, circular, polygonal, or, very rarely, linear. They tend to remain on paper because real life leads to compromise. Brasilia (a built Utopia of original shape that is another surprising omission from this book) quickly became engulfed in messy shantytowns as the normal order reasserted itself.