Technological historian and architecture critic Lewis Mumford wrote in "Yesterday's City of Tomorrow" that the extravagant heights of Le Corbusier's skyscrapers had no reason for existence apart from the fact that they had become technological possibilities. The open spaces in his central areas had no reason for existence either, Mumford wrote, since on the scale he imagined there was no motive during the business day for pedestrian circulation in the office quarter. By "mating utilitarian and financial image of the skyscraper city to the romantic image of the organic environment, Le Corbusier had, in fact, produced a sterile hybrid."