Back in the early 20th century, the baseball pitcher Walter Johnson confounded opposing batters by throwing the fastest fastball they’d ever seen. “You can’t hit what you can’t see,” they would say.

A century later, it’s an apt saying for those navigating this unusual moment.

The surreptitious and the invisible are defining the human landscape during these weeks in ways we are only barely beginning to understand. There is, of course, a fast-moving and elusive new virus. But the attitudes and fears that have emerged in the battle against it can be equally unsettling.

Now the entire world — its physical well-being, its economy, its people’s livelihoods — is being upended by something unseen and aggressive and hard to avoid. Is it any wonder that unease and disorientation are the result?

“There’s this invisible threat of a virus, but then there are visible threats of me losing my job or my livelihood or the economic shutdown or my mental health because I’m isolated,” says Lindsey Root Luna, a clinical psychologist who teaches at Hope College in Michigan.

“So I look at the fact that I have both a visible threat and an invisible one,” she says. “And people tend to respond to the visible threat.”

The coronavirus is an apt adversary for our times. It’s a specific threat, yet its invisibility has made it a Petri dish where people can cultivate all kinds of misinformation.

Already, this was an era when entertainment and politics screamed: Even if you can see it, don’t necessarily believe it. In the United States, which has been full-on grappling with the coronavirus since isolation began in mid-March, it resonates especially potently.

To begin with, American life is a 400-year exercise in wrestling invisible ideals into something tangible — a functioning country and its laws. That country, shaped by visuals and concrete things and loud volumes, sits today at a particularly weird juncture when people with agendas use those loud volumes and sophisticated visuals to call even the most concrete things into doubt.

On top of that, enough is coming at people already that many resist or reject storylines involving more abstract or unseen forces — a virus, political manipulation, climate change.

“We are evolved to respond to threats that exist — a car crash, a punch in the face — that we can perceive at that level,” says Alix Spiegel, co-host and co-producer of the NPR program “ Invisibilia,” which tells stories that add structure and context to things we can’t see.

“But when they exist on a physical scale or a time scale that is hard for us to relate to, then we’re much, much worse at coming up with the appropriate actions,” Spiegel says.

This is evident in the reactions to antivirus measures taken by authorities. Many comments echo this observation: We can’t see this getting worse where we are, so let’s fix the urgent problem we already can see — the collapse of life around us.

“From a visible perspective, nothing’s changed. Very few of us actually see someone suffering from coronavirus,” says Adam Kotsko, who teaches at North Central College in Illinois. He is the author of “ The Prince of This World, ” a history of one of humankind’s most notorious unseen adversaries — the devil.

“Society,” Kotsko says, “has been thrown into upheaval for no visible, apparent reason.”