Not a single drop of water passes over the same rock twice, and the murmur of water rushing over a rock is constantly changing. Sameness is but an illusion of the human ears, eyes, mind. Water that has once flowed along a riverbed can never retrace its course. Human life is no different. It is only our mundane eyes and minds that we see yesterday as being the same as today.

Enlightened eyes and minds should recognize that each moment has a form different from that of any other moment

Shundo Aoyama, Zen Seeds