According to David M. Eagleman
Your brain, after all, is encased in darkness and silence in the vault of the skull. Its only contact with the outside world is via the electrical signals exiting and entering along the super-highways of nerve bundles. Because different types of sensory information (hearing, seeing, touch, and so on) are processed at different speeds by different neural architectures, your brain faces an enormous challenge: what is the best story that can be constructed about the outside world?
The days of thinking of time as a river—evenly flowing, always advancing—are over. Time perception, just like vision, is a construction of the brain and is shockingly easy to manipulate experimentally.
By the way, how did Chagall’s “Le temps n’a point de rives” (the one with the fish and the clock) come to be called in English “Time is a river without banks”? As discussed here, the name is taken from a poem by de Lamartine, who said
L’Homme n’a point de port, le temps n’a point de rives;
Il coule et nous passons!
Man has no harbor, time has no shore;
It flows and we pass!