You would not know, but it would consume your entire being.
Imagine a disaster.
Whether it is an earthquake, a tornado or a hurricane, what comes to mind is a catastrophic moment in which lives are upended, homes torn apart, and families scattered. When the disaster ends, the rebuilding begins. Schools are erected, homes renovated, and so on.
The psychological damage takes longer to heal. A disaster creates uncertainty. You may not know where your next meal is coming from or where you'll sleep tonight. You might not know where your brother, sister, mother or father is. Do you have a job anymore? Can you survive anymore?
A disaster is not just the single moment when the roof is torn from your home. It lasts until you are again as secure as you were before the disaster.
Right now, Alaska ─ my home state ─ is in economic turmoil. With oil prices plunged, there's a multibillion-dollar deficit. The state's savings accounts will last, but not for more than two years at the outside. Thousands of people have lost their jobs, and thousands more will lose theirs.
This isn't a disaster like a hurricane or a tsunami, but it's a disaster nonetheless.
In this disaster, the state's governor has argued, the enemy isn't the deficit ─ it's the uncertainty it brings. As long as the deficit exists, people are uncertain about what will be done to fix it. Will they lose their jobs? Will they have to move? Can they truly risk buying a home, starting a new business, purchasing a new car?
Uncertainty creates stress, paralysis and fear. When the uncertainty is great enough, it can cause terror.
I mention this only to give you a doorway by which to experience what the mood must have been in Moscow in 1937. A previous commenter claimed that the Great Terror impact on an ordinary Soviet citizen was "not very much."
That's probably the biggest error I've ever seen on /r/askhistorians that wasn't deliberate Holocaust denial.
The effects of the Great Terror ─ Robert Conquest coined that term, and it is appropriate ─ were felt at every level of Soviet society in a drastic and unforgettable way. To quote Norman Naimark's Stalin's Genocides:
"The term captures well the 'apocalyptic theater of horrors' of those two years in which every Soviet citizen, with the exception of the vozhd himself ─ Stalin ─ could potentially be arrested, tortured, exiled, or executed. The fear was palpable and, especially for those in any position of responsibility ─ the nomenklatura of the party, factory bosses, intellectuals, army generals, and newspaper editors ─ bags were packed in case the knock on the door came ..."
Various professions endured particular attention. As Karl Schlögel writes in Moscow 1937 (first published in German, but available in English since 2013), demographers, statisticians, geologists ─ even mountain climbers ─ earned special attention from the purge. These were not high-ranking officials, just ordinary people in the bureaucracy created by the Soviet system.
In the 1930s, that bureaucracy was booming as the Soviet Union embarked on one of the great modernization campaigns of human history. Victor Fischer, one of the last surviving creators of the Alaska Constitution, grew up in Moscow during the Great Purge. In his memoir, To Russia with Love, he recalls how he and school classmates had great fun playing around the city in the vast construction sites that dotted it.
In his book, Schlögel makes the case that the soaring Soviet expansion efforts inevitably ran into teething problems. Amid the excesses of the Great Terror, people assigned to these projects were executed as "wreckers" or "saboteurs" of the state. Take the Moscow-Volga canal, whose opening coincided with the arrest, prosecution and execution of its overseers, or the way problems with the swelling Soviet railway system led to a hunt for saboteurs that inevitably killed the innocent.
The Great Terror is typically divided into two sections, the one before August 1937 ─ which was focused on the party and government's elite ─ and the period after August 1937, where the executions spread.
As Montefiore writes in Stalin: The Court of the Red Tsar:
"Here, on the contrary, death was sometimes random: the long-forgotten comment, the flirtation with an opposition, envy of another man's job, wife or house, vengeance or just plain coincidence brought the death and torture of entire families. This did not matter: "Better too far than not far enough," Yezhov told his men as the original arrest quota ballooned to 767,397 arrests and 386,798 executions, families destroyed, children orphaned, under Order No. 00447."
The Terror grew and grew because the Stalinist system of denunciations combined with the Soviet love of quotas and overfulfilling them. Anyone who overfilled their quota, whether that quota was the manufacture of shoes or of executions, could expect rewards. Denunciations were an easy way to file grievances and cover your own skin. As Montefiore writes: "Once the Terror was unleashed, denunciations worked like kerosene on a fire, keeping it flaring up. These denunciations were already a vital part of the Stalinist system: everyone was expected to denounce everyone else. In the Bolshevik universe, there were only two ways for mistakes to come to the notice of the leaders: accidents ─ and denunciations."
As /u/TenMinuteHistory points out, these denunciations (and the punishment for them) could be arbitrary. Again, the uncertainty is what made the Great Terror a disaster that affected far more people than were killed or imprisoned. The fear spread because anyone could be taken away in the middle of the night, with little cause. There was no rule of law, no regulated process for appeal and hearing. The Great Purge went through the motions of a trial, but if an execution was decided, it would come quickly.
The most common estimates claim that the Terror resulted in 1.5 million arrests and more than 700,000 executions. These were no small figures. Going by the 1940 U.S. Census, it would be as if every person in Pittsburgh was taken into a basement and shot. Every person in Los Angeles would be deported to camps throughout the Rocky Mountains or Alaska.
The Great Terror was not limited to a certain age, gender, economic class or geographic area. In 2000, Melanie Ilic published "The Great Terror in Leningrad: A Quantitative Analysis". In Leningrad, the victims of the Great Terror ranged from 19 to 78 years of age. Fewer than 4 percent were women. While most purge victims were ethnic Russians, minorities sometimes suffered disproportionately. Poles, for example, made up 16 percent of the purge's victims, even though they were less than 1 percent of the USSR's population nationally. Ethnic Germans were purged in large numbers due to fears of war with Nazi Germany.
Even Americans were subject to the purge. In 2008, Tim Tzouliadis published The Forsaken: An American Tragedy in Stalin's Russia, which detailed the plight of the thousands of Americans who emigrated to the Soviet Union to the Great Depression. They came seeking jobs and security from economic uncertainty ─ the Soviet Union, locked out of global trade, was surging while the world faltered in the Depression ─ but within a few years, they found the Great Terror.
Ford Motor Company, in the midst of the Depression, made a deal with the Soviet Union to construct a huge factory complex in Gorky. Hundreds of Americans emigrated to the Soviet Union to work there. Many were devoted communists seeking "true socialism." Instead, the Terror ate them.
On Oct. 7, 1937, Pravda published an article accusing the new factory of "shameful" work, Tzouliadis explains. "Wreckers" had ruined machinery with "carelessness and insufficient care," which was the logical explanation for why the new plant could not match the production of the automobile works in Detroit. In describing what happened to one particular family, part of the nascent 1930s Soviet baseball circuit, Tzouliadis writes:
"THROUGH THE COURSE of 1937 and 1938, Americans such as Victor Herman began to disappear, one after another. Many of the arrested were shot not long afterward, often with their fathers, who had brought them to the USSR. After their denunciation, the baseball players from Boston, Arthur Abolin and his younger brother, Carl, were both arrested and executed with their father, James Abolin, in 1938. Their mother died later, in a concentration camp. Only their younger sister, Lucy Abolin ─ the precocious drama student of the Anglo-American school ─ was left untouched."
These are the stories of the men, women and children who died. The Terror didn't just touch them: It touched every person who lived in the Soviet Union. This was a disaster of catastrophic proportions, but unlike a hurricane's winds or an earthquake's shaking, it did its damage as much with the uncertainty and terror left in the minds of its victims as it did with the bullets fired from a gun.