Michael Wolf / laif / Redux

Privacy is mostly an illusion. A useful illusion, no question about it, one that allows us to live without being paralyzed by self-consciousness. The illusion of privacy gives us room to be fully human, sharing intimacies and risking mistakes. But all the while, the line between private and public space is as porous as tissue paper. The adulterous couple sneaking off to a hotel: Is someone following them? The teenagers skipping school to visit the mall: Will they bump into a woman from Mom’s book club? The solitary motorist thrashing an air guitar at a traffic light: Will the driver in the next lane look over? Like children of a certain age who think closing their eyes will make them invisible, we assume that no one sees or hears our private moments, and we’re right—until someone watches or listens.

This was true long before the National Security Agency began collecting our telephone and Internet records from technology and communications companies, and long before the House of Representatives on July 24 gave a fresh thumbs-up to further NSA collections by a narrow 12-vote margin, 217-205. It was true long before a military judge found Private Bradley Manning guilty of espionage for his role in the WikiLeaks case—but acquitted him on the charge of aiding the enemy—on July 30. The illusive quality of privacy is a recurring theme of literature going back to the Hebrew Bible. Consider beautiful Bathsheba, who strips for a bath in the second Book of Samuel, an ancient text, only to come under the lustful gaze of King David, pacing on his palace rooftop. Or Hamlet, whose private conversation with his mother is overheard by Polonius, hiding behind the drapes. The great filmmaker Alfred Hitchcock was fascinated by secrets that would not stay hidden and made a masterpiece, Rear Window, from the premise that entire lives (and deaths) are on display behind the uncovered windows of anonymous cities, just waiting for a watcher to decrypt them.

But the revelation of the NSA’s vast data-collection programs by a crusading contract worker, Edward Snowden, has made it clear that the rise of technology is shattering even the illusion of privacy. Almost overnight, and with too little reflection, the U.S. and other developed nations have stacked the deck in favor of the watchers. A surveillance society is taking root. Video cameras peer constantly from lamp poles and storefronts. Satellites and drones float hawkeyed through the skies. Smartphones relay a dizzying barrage of information about their owners to sentinel towers dotting cities and punctuating pasture-land. License-plate cameras and fast-pass lanes track the movements of cars, which are themselves keeping a detailed record of their speed and location. Meanwhile, on the information superhighway, every stop by every traveler is noted and stored by Internet service providers like Google, Verizon and Comcast. Retailers scan, remember and analyze each purchase by every consumer. Smart TVs know what we’re watching—soon they will have eyes to watch us watching them—and smart meters know if we’ve turned out the lights.

(MORE: TIME’s full coverage on privacy)

And the few remaining technical barriers to still more surveillance are falling before the awesome force of 1s and 0s, the binary digital magic that is the fuel of revolutionary change. Until recently, there were hard physical limits on the number of pictures that could be developed, videotapes that could be stored, phone–company records that could be typed or photocopied or packed into boxes—let alone analyzed. Now the very idea of limits is melting away. In 1980 (not that long ago; Barack Obama was in college), IBM introduced its Model 3380 disk drive, the first device capable of storing more than a gigabyte of data. It was roughly the size and weight of a refrigerator and cost an inflation adjusted $100,000. Today a flash drive costing one-thousandth as much can store 50 times the data and fit on a key ring. The amount of data that can be stored is nearly infinite. In a prescient series of blog posts several years ago, Princeton computer-science professor Edward Felten explained that this tremendous growth in storage capacity would inevitably spur intelligence agencies to collect all available data—everything—simply because it’s cheaper and easier than trying to figure out what to take and what to ignore. “If storage is free but analysts’ time is costly, then the cost-minimizing strategy is to record everything and sort it out later,” Felten noted.

That is precisely what has happened. And at the same time, ever more sophisticated computer algorithms make it possible to sift through and analyze larger and larger slices of that data, raising social and ethical dilemmas that cannot be ignored. The future is here. Nearly everything that happens from now on has the potential not just to be seen by some restless King David or overheard by an eavesdropping Polonius but also stored indefinitely. Government agencies, and the private corporations working with them, collect and store billions of records every day, and they’re hungry for more: not just phone records and Web addresses but e-mails, texts, downloads, medical records, retail receipts, bank balances, credit-card numbers and travel itineraries.

The world glimpsed a corner of this future in April, when two bombs went off at the finish line of the Boston Marathon. The scene was chaos. The bombers had vanished. Yet within a few hours, their faces were plainly visible on TV screens around the world. It turned out that every nefarious move they made as they delivered their deadly packages to Boylston Street had been scanned and stored by surveillance cameras. Their quick capture was a triumph for law enforcement but left an unsettling realization in its wake: everyone else on those teeming Boston sidewalks was also being watched and remembered.

Then, just weeks after Boston, the slight and pallid Snowden emerged from his NSA cubicle to warn us that surveillance goes far beyond the tireless eyes of the cameras. Every phone call placed, every Web page visited—billions and trillions of data points, like raindrops in a monsoon—is captured daily and stored for possible analysis by the U.S. government. Remember the time you pocket-dialed your sister? The time you Googled your college flame? The day you did that thing you so deeply regret—that thing you thought was private—involving a Web search or a phone call or a text or an e-mail? It’s all there. In fact, the government, with the NSA as the lead agency, is this moment busy building the world’s largest data storage facility in Utah. More than a million square feet, room enough to preserve everything, for the time being.

The government calls the material it collects metadata, instead of plain old data. The difference, it might seem, is the difference between a haystack and the needles hidden inside. No one cares about the hay; they hardly touch it as they search intently for the telltale glint. Perhaps a better analogy would be a catalog at the Library of Congress, which stores some 35 million books and other print publications, most of which no one ever opens. Why so many? Because it is easier to have publishers send one of everything than to choose which publications to preserve. (And who knows what, in that vast reserve, might be needed someday?) In any event, the government assures us that as long as we don’t consort with menaces to national security, our phone calls and Web searches are of no more interest to Uncle Sam than an outdated tome on Bolivian agronomy.

(MORE: A Glossary of Government Surveillance)

Across the political spectrum, from ACLU Democrats to Ron Paul libertarians, Americans are skeptical of the metadata fig leaf. According to a poll on July 26 by the Pew Research Center, only about 1 in 5 people surveyed believe the government actually keeps its nose out of private phone calls and emails. The same small minority trusts government claims to use the surveillance trove only for anti-terrorism purposes. Indeed, more Americans in the survey think Uncle Sam is hacking their personal communications (roughly 1 in 4 respondents) than have faith in the government’s explanations. The skeptics no doubt have noticed that governments are made up of people and that people are prone to misuse information when driven by greed or curiosity or a will to power. The current IRS scandal, in which the agency’s rules may have been bent to political ends, could prove to be an apt example. Somewhere in the vast NSA collections are data trails belonging to political foes, unpleasant neighbors, feuding ex-spouses, bankable celebrities—and it takes no great imagination to see the temptation for corrupt bureaus or individuals to take a look around.

What’s to stop them? In a recent speech at the Brookings Institution, Robert Litt, general counsel to the Director of National Intelligence, sought to answer that question. He argued that strong measures are in place to protect the privacy of Americans as their data accumulates on government silicon. Surveillance programs are administered by the Executive Branch, overseen by Congress and supervised by the Judicial Branch, through the super secret FISA court. The fact that most of these checks and balances take place behind closed doors does not make them toothless, Litt maintained.

Take the specific case of a suspected foreign terrorist known to have communicated by phone with U.S. citizens. Litt detailed a litany of privacy safeguards that government sleuths must honor as they investigate the records. “We allow only a limited number of specially trained analysts to search these databases,” he explained, and “even those trained analysts are allowed to search the database only when they have a reasonable and articulable suspicion that a particular telephone number is associated with particular foreign terrorist organizations.” Moreover, the FISA court must certify that the terrorist connection is based on a valid suspicion, supported by information “documented in writing and approved by a supervisor.” Even after all this, the analysts are “allowed to use this information only in a limited way, to map a network of telephone numbers calling other telephone numbers,” Litt continued. And finally, the analysts don’t know the names that match the phone numbers.

(MORE: Americans Sharply Split on Privacy Issues)

Since the Snowden disclosures, further protections have been suggested. Perhaps the government should employ a team of skilled attorneys, with appropriate security clearances, to argue against the sleuths before the FISA court—to ensure that the judges hear strong arguments against snooping. Another suggestion is to declassify FISA court proceedings, to the extent possible, so the public can better understand what’s going on. Even without those additional steps, however, a majority of Americans support the current arrangement, even if they don’t entirely trust the government’s explanations. According to a recent Washington Post/ABC News poll, after digesting Snowden’s news, a solid majority feel that it’s more important to fully investigate terrorist threats than to protect personal privacy.

While the scope of surveillance today is much broader than in the past, Americans long ago grew accustomed to limits on privacy. The Supreme Court has held that information voluntarily given to third parties is no longer secret, nor can we expect privacy to cloak our actions in public places or our communications via the public airwaves. The government can intercept radio signals and is allowed to read what’s written on the outside of our mail. It’s just a step—granted, a large step—from those principles to the ones that underpin today’s massive data collections. The header of an e-mail is not so different from the face of an envelope, nor is the signal from a tablet to a wireless router entirely unlike the signal from one radio to another.

We have also learned to trade elements of our privacy for all sorts of supposed benefits. Google tracks our searches so that it will know which advertisements to show us. Smartphones record our locations to be more helpful in steering us to the nearest multiplex, restaurant, gas station or church. Drugstores analyze our purchases to reward us with coupons redeemable on a future visit. And so on. We want our gadgets to know us intimately—want our thermostats to know when we’re cold, want our toasters to know how we like our bagel, want our search engines to know what we’re looking for even when we misspell it. So far, we have been willing to pay for that intimacy in lost privacy.

Which brings us to a strange crossroads. The more technology endangers our privacy, the less we seem to prize it. We post family photos on social-media sites and ship our credit-card numbers to total strangers. We ask websites we’ve never visited—designed by people we’ve never met—to give us advice on treating embarrassing maladies and hunting for potential mates. But the government is different, as Litt acknowledged in his recent speech, because “the government has the power to audit our tax returns, to prosecute and imprison us, to grant or deny licenses to do business and many other things. And,” he continued, “there is an entirely understandable concern that the government may abuse this power.”

In recent years, privacy advocates have persuaded the Supreme Court to require search warrants before police can sneak GPS trackers onto suspects’ cars or scan houses from the outside using infrared devices that sense the telltale heat signature of marijuana grow lights. Such steps seem small, however, compared with the rapid rise of surveillance powers and the grim history of governments corrupted by the temptation to watch their peoples too closely. The admirable goals of public safety and national security have been exploited time and again by intrusive regimes around the world seeking to spy on their critics and smother dissent. Americans need only read the Bill of Rights to see that suspicion of government intrusion is a national birthright. As tools for prying grow in number and strength, this is no time to stop being suspicious.

(MORE: Privacy and the Law: How the Supreme Court Defines a Controversial Right)

Perhaps there’s consolation in the magic of the microchip. Technology makes all secrets more difficult to keep—not just our personal secrets but the government’s as well. Again and again over the past dozen years, the methods, mistakes and misdeeds of the world’s most powerful government have been unmasked by lowly employees convinced that what they are witnessing is wrong. From the photos at Abu Ghraib prison to the avalanche of WikiLeaks documents to the Snowden disclosures, large caches of data have been loaded onto thumb drives or burned onto wafer-thin discs—then spread around the globe in the blink of an eye. Though the clarions may be prosecuted, the facts they reveal cannot be recalled or repressed.

This, ultimately, may prove to be our strongest protection against the rise of the surveillance state. The same tools that strengthen it strengthen those who protest against it. Privacy is not the only illusion in the new age of data; government secrecy is too. Big Brother might be watching, but he is also being watched.

—with reporting by Massimo Calabresi