They say if you throw enough rocks into a lake, it will become just a flat field. If you keep throwing rocks at the same place, a mountain will appear. On one side, after a long time, and with enough rocks, you could build a mountain in your life time where the lake once lay. On the other, if you just leave it to the countless generation of rock throwers, the lake will get filled, and then a mountain, if they kept on throwing rocks. You could also just let it be, and enjoy the lake as it is. You have choices, goals (and survival) whether to throw the rocks or not into the lake. Metaphorical speaking, or physically applied, replacing anything with something else, is something we do really well.
While I was sitting on the beach, I was contemplating these thoughts as I saw a family throwing rocks into the lake, skipping them along the water’s surface. Oh what silly things the mind ponders on a hot spring day as the ripple of the water dances along the shore in the Sun’s light. I challenged my thought experiment by adding in that the possibility of another Ice Age creeping in, and carving out the valley again, before we could get the last stone that fills the lake in, is vary likely.