Nearly two thousand years before Rudolph Clausius and Lord Kelvin first expressed the second law of thermodynamics (although there is debate on whether or not the French physicist Sadi Carnot discovered it earlier), Marcus Aurelius was musing on it. “Bear in mind,” he wrote, “that everything that exists is already fraying at the edges and in transition, subject to fragmentation and to rot. Or that everything was born to die.”That is to say: We are all subject to entropy. Science has since confirmed it into immutable law. We cannot eliminate disorder from the system, no matter how much we try. Everything we build, including ourselves, is constantly breaking down. What does this mean for us? First, it should bake in humility. We are building sand castles. Even our real castles eventually fall into the sea or crumble into dust. Second, it demands presence. This moment is all we have. So enjoy it. Drink it in. Appreciate it.But also be prepared to let it all go. Because it’s going, whether we like it or not. That’s the law.