You of the west,' Malik said, 'think of time moving in a straight line, from past to present to future. You eastern brothers regard time as a circle, returning endlessly in a cycle of decay and rebirth. Both ideas have a dimension of the truth. If you were to combine geometrically the movement of the circle with the movement of the line, what would you have?' He snapped his mouth shut and peered at me with an uncanny resemblance to my old schoolmaster. 'The spiral?' I ventured. 'Yes, yes. Or the helix. They are our models of the passage of time.' he said. 'So time moves on, but history repeats itself.' 'Precisely,' he said