Most crimes are petty. Shop lifting, for instance, spikes over the holiday season. Maybe crimes of passion do so as well. They’re the result of “affairs,” formerly spoken of as adultery and fornication.

Some crimes are heinous, and they make the front page. Last week a serial killer confessed to killing 90 women over a period of decades. He’s offered convincing accounts of his acts of femicide. Now, aged and in bad health, he’s waiting to die in a Texas prison.

What else? We’re increasingly aware of senseless killings and cowardly acts of terrorism. Violence against someone who poses no threat is “senseless” in a straightforward way. But terrorist acts rarely show physical cowardice. They are called “cowardly” to insult their perpetrators. Walker Percy, in his Love in the Ruins, introduces a memorable character (a Dallas-based proctologist) who dismisses race-related crimes as “the work of madmen.” After all, why bother to look for the causes of such crimes?

So, then, what is an unspeakable crime? Here’s a way to understand it, with a tip of the hat to Mark Twain. Remember Huck Finn? He helps his friend Jim, a runaway slave, to escape. The twist is that Huck feels guilty about doing so. He says that he’s going against his conscience. But he’d also “feel bad” if he didn’t help Jim. So what’s he to do? He wonders, “What’s the use you learning to do right when it’s troublesome to do right and ain’t no trouble to do wrong, and the wages is just the same?”

Huck’s problem, though, is that he misread his own conscience because of what some call a “corruption of consciousness.” Huck rightly helped Jim, but he could not express why he was right. A deeply disordered culture had corrupted his consciousness by suppressing the concepts and language he needed to identify slavery for what it is: an unspeakable crime. Such are the crimes one does not speak of because one lacks the capacity to do so.

There’s nothing new about the corruption of consciousness as a moral phenomenon. Highly choreographed human slaughter in the form of gladiatorial combat was for centuries central to Roman life. Among classical authors only Seneca, who died at the command of Nero’s mother, disputed its legitimacy. As for the rest, patrician or plebeian, they were speechless. The crime on which so much of public life turned was, for them, unspeakable. They had neither the eyes to see it nor the language with which to condemn it.

Nor, of course, are unspeakable crimes relics of the past. Apart from prophets and the few who listen to them, the corruption of consciousness is fearfully at work among us. Two examples come to mind. The first is that on a global level some 50 million unborn children die by abortion each year. Their hidden deaths are silent. They are increasingly ignored and increasingly “unspeakable.” The second example is what is termed nuclear deterrence. It has sometimes been called what it is: mutual assured destruction. Various heads of state are even now retooling and re-marketing the structures that keep it in place.

May the Lord of Life give us the grace to break the silence that shrouds this pair of unspeakable crimes!