To consider the city as the projection of society on space is both an indispensible starting point and too elementary an approach. For, although one must go beyond the empiricism of geographical description, one runs the very great risk of imagining space as a white page on which the actions of groups and institutions are inscribed, without encountering any other obstacle than the trace of past generations. This is tantamount to conceiving of nature as entirely fashioned by culture, whereas the whole social problematic is born by the indissoluble union of these two terms, through the dialectical process by which a particular biological species (particularly because divided into classes) "man", transforms himself and transforms his struggle for life and for the appropriation of the product of his labour.