Herakleitos of Ephesus may have been the first to articulate the idea that the world is in a state of flux when he said that ‘everything flows’ (ta panta rhei). People before him had noticed that things change, but he made a lasting reputation by extending the reach of the idea. It was not only individual creatures that changed – by growing up and growing old – but also the mountains, the clouds and the stars in the heavens. The change could be so slow that a person's lifespan might not be long enough to notice it, and at the time (around 500 BCE) it was not exactly reasonable for Herakleitos to have this conviction, but in our age it is the conventional wisdom. Monumental architecture has generally set itself against change. The ancient Egyptian pyramids are a powerful emblem of the appeal of the illusion of permanence. The purity of their Euclidean geometry makes them seem surprisingly modern and therefore, given their age, timeless; but that too is an illusion. Le Corbusier defined architecture as ‘the masterful, correct, and magnificent play of volumes brought together in light’, 1 and it is a view that the pyramids exemplify: eternal authoritative form in brilliant light at the edge of the desert – prismatic triangles set against the cloudless sky and endless horizon.