“One cannot step twice in the same river.”

“One cannot step twice in the same river.” – Heraclitus (ca. 540 – ca. 480 BCE)
Heraclitus definitely isn’t alone here. His message was that reality is constantly changing it’s an ongoing process rather than a fixed and stable product. Buddhism shares a similar metaphysical view with the idea of annica, the claim that all reality is fleeting and impermanent.
In modern times Henri Bergson (1859 – 1941) described time as a process that is experienced. An hour waiting in line is different from an hour at play. Today contemporary physics lends credence to process philosophy with the realization that even apparently stable objects, like marble statues, are actually buzzing bunches of electrons and other subatomic particles deep down.