【明報專訊】THE PASSAGE OF TIME has attracted much attention from both Eastern and Western philosophers. For example, Heraclitus, an ancient Greek philosopher, famously said that "You cannot step twice into the same river, for fresh waters are ever flowing in upon you." His version of time reflects the ever-changing nature of the world. In contrary, according to Lao Tzu (老子), Tao (道) is still and formless, "standing alone, and undergoing no change". He emphasised the eternal order of the world.