the tide will inevitably come in and sweep the sand castle away

“We are like children building a sand castle. We embellish it with beautiful shells, bits of driftwood, and pieces of colored glass. The castle is ours, off limits to others. We’re willing to attack if others threaten to hurt it. Yet despite all our attachment, we know that the tide will inevitably come in and sweep the sand castle away. The trick is to enjoy it fully but without clinging, and when the time comes, let it dissolve back into the sea.”
― Pema Chödrön, When Things Fall Apart: Heart Advice for Difficult Times