“Happy families are all alike; every unhappy family is unhappy in its own way.”
Societies evolve. We have no idea of how it happens, but in a short time societies can be transformed.
In the XVIth century, the Soshone of the Great Plains of North America migrated east in response to climate change. Most turned north, following the bison herds on foot. A bunch of Shoshone migrated south to meet the Ute, the horse, and the gun. Within a few generations, they transformed themselves into fierce Comanche nomads. They established the Comancheria in what is not much of Texas, an empire which lasted until 1875.
Strategically placed between Mexico, French Louisiana and its successor state the US, the Comanche drew primary sustenance from riding buffalo herds to their doom. Barbecued buffalo steaks (and tongue) are fantastic, but the human diet also needs carbohydrates. In response to this dietary constraint the Apache evolved toward semi-settling life by growing their grains along the rivers. Guns, horse, and trade (in slaves) enabled the later arriving Comanche to develop a raiding and trading empire that lived off the surrounding powers. In the process they displaced the Apache from the rolling Plains of Texas. This is nothing unusual: nomads either displace agriculturalists, or they conquer them but become “acculturated” (descendants of northern Nomads ruled the Chinese Empire for half of its duration).
Societies evolve. It is not “whiggish” progress – rather it is “descent through modification”. Contrary to belief of the illuminist philosophers in France, there is nothing inherently benign in societal change. Societies can spiral into self-destructive behavior as well as move along a virtuous trajectory.
We love uplifting tales of virtuous progress. Tales of societal decay come second: they are redolent of decadent “what ifs” and “opportunities missed” and the stuff of romantic narratives of impending tragic doom. We hardly know how societies break out self-destructive behavior.
It may be a matter of circumstance. When Stalin died, the new Politburo faced several tasks. The membership had to unify, after years of fierce rivalry in competition for Stalin’s favor as well as in preparation for the aftermath to his death. It also had to win at least the acquiescence of the Soviet masses. The Party had to deliver more “butter” to make up for the sacrifices of WWII and those of reconstruction. At the funeral the new leadership promised “butter” and let it be known to the US that it was ready to contemplate “peaceful coexistence”.
The ambivalent American response decidedly influenced the jockeying for power and policy inside the Kremlin. Eisenhower saw a strong economy enabling American success – he pleaded for disarmament. Dulles preferred the directive approach of “roll back” of Communism through power – both strong and soft. In the race to consolidate his personal power, Beria brought onto the table the option of Germany’s reunification under the flag of neutrality. The rest of the leadership used this initiative to discredit Beria and kill him..
Terror stopped in the Soviet Union. To be more precise: the style shifted from mass to exemplary and targeted terror. Acquiescence of the masses no longer rested on terror: it was “bought” with butter and economic development. That is how the Soviet Union stopped the self-destructive involution. It is no patent medicine, however. When the Communist leadership grabbed for this strategy anew in 1985 as the Politburo attempted to lift the Soviet Union out of economic and cultural stagnation (another form of terror if you wish), the system collapsed. The Soviet Union did not survive glasnost and perestroika.
This reflection points to a fundamental difference between secular and theocratic totalitarianism. Theocratic totalitarianism does not envisage the option of a Thermidor. Theocracy, that is, does not provide for Paradise on earth.
 See Pekka HÄMÄLÄINEN (2008): Comanche empire. Yale University Press, New Haven.
 See: Jared DIAMOND (2004): Collapse: How Societies Choose to Fail or Succeed. Viking, New York. The facts in this book are increasingly disputed. The core point, that some societies succeed while others fail, remains valid.
 See: Bronslaw BACZKO (1989): Comment se sortir de la Terreur. Thermidor et la Révolution. Gallimard, Paris.
 Melvyn P. LEFFLER (2007): For the soul of mankind. The United States, the Societ Union, and the Cold War. Hill & Wang, New York.