The quote "Eventually all things merge into one and a river runs through it" is found in the final passage of Norman Maclean's autobiographical novella A River Runs Through It:
Like many fly fishermen in western Montana where the summer days are almost Arctic in length, I often do not start fishing until the cool of the evening. Then in the Arctic half-light of the canyon, all existence fades to a being with my soul and memories and the sounds of the Big Blackfoot River and a four-count rhythm and the hope that a fish will rise.
Eventually, all things merge into one, and a river runs through it. The river was cut by the world's great flood and runs over rocks from the basement of time. On some of those rocks are timeless raindrops. Under the rocks are the words, and some of the words are theirs.
I am haunted by waters.
What does he mean by "Eventually, all things merge into one, and a river runs through it."?