Architect Rem Koolhaas in his 1978 book "Delirious New York" comments that it created "undreamed-of freedom for three-dimensional anarchy," and called it "the most courageous act of prediction on Western civilization." Koolhaas celebrated the city's "poetic density" and sees the architecture of Manhattan as "a paradigm for the exploitation of congestion"; indeed he applauds the city's "culture of congestion." Because of the "magic carpet of the Grid", "all blocks are the same, their equivalence invalidates, at once, all the systems of articulation and differentiation that have guided the design of traditional cities. ... made the history of architecture and all previous lessons of urbanism irrelevant. It forces Manhattan's builders to develop a new system of formal values, to invest strategies for the distinction of one block from another."