The ancient Greek philosopher Haraclitus famously mused that "no man ever steps in the same river twice, for it's not the same river and he's not the same man."
It is a concept that demonstrates the change that occurs in all of humanity throughout the course of a lifetime. The circumstances of the environment are always in flux, the man different with each step he wades through the water – wiser from the step he took before.
And extrapolated, it means no individual in life crosses the same river to reach the other side. No path is the same, regardless of the destination.