Technology contains no inherent moral directive—it empowers people, whatever their intent, good or evil. This has always been true: when bronze implements supplanted those made of stone, the ancient world got scythes and awls, but also swords and battle-axes. The novelty of our present situation is that modern technology can provide small groups of people with much greater lethality than ever before. We now have to worry that private parties might gain access to weapons that are as destructive as—or possibly even more destructive than— those held by any nation-state. A handful of people, perhaps even a single individual, could have the ability to kill millions or even billions. Indeed, it is possible, from a technological standpoint, to kill every man, woman, and child on earth. The gravity of the situation is so extreme that getting the concept across without seeming silly or alarmist is challenging. Just thinking about the subject with any degree of seriousness numbs the mind. The goal of this essay is to present the case for making the needed changes before such a catastrophe occurs. The issues described here are too important to ignore.