The fields of Ypres, 1915. A ghostly green cloud creeps across no-man's-land, bringing unspeakable agony to soldiers in its path. This was humanity's first mass experiment with chemical warfare. Turning the very air into a weapon. In that moment, we crossed a threshold that had stood for millennia. The ancient taboo against poisoning your enemy.

Yet something strange happened next. Instead of chemical weapons becoming normalized, we recoiled from them. Not just governments signing protocols, but soldiers themselves. Even in WWII, when every other weapon was fair game, both sides largely refrained from gas warfare. It was policy. And it was visceral. Something in our collective soul recognized we'd gone too far.

This pattern keeps repeating throughout history. We develop new forms of cruelty, but our capacity for empathy expands to reject them. Public executions were once entertainment; now they sicken us. Slavery was once global; now it universally horrifies. Each time we touch the darkness, we build new moral antibodies against it.

What's remarkable isn't just that we make rules against atrocities; it's that these rules actually stick. The Geneva Protocol wasn't perfect, but chemical weapons never again saw the widespread use of WWI. When they are used today, like in Syria, the global reaction is immediate and visceral. We've developed a kind of moral immune system.

We are far from perfection. We still wage war, still cause suffering. But we've developed boundaries that would baffle our ancestors. Precision strikes to minimize civilian casualties, international aid for enemy populations, trials for war crimes. We still do horrible things to each other. But each new horror we invent teaches us where the lines must be drawn.

This is what spiritual growth looks like on a species level. It’s not a smooth ascent to enlightenment. It’s a series of harsh lessons that gradually expand our circle of concern. We learn our hardest lessons in the darkest places, like those fields of Ypres where we first saw what we could become, and chose a different path.

Today, as we develop AI, genetic engineering, and weapons that could end civilization, we face similar choices. Will we recognize the lines we must not cross before we cross them?