In an interesting paper he tweeted yesterday, Kaushik Basu discusses, using a mathematical model, an old problem: how rulers once they are in power cannot leave it even if they wish to do so, because their road to power, and in power, is littered with corpses that will all (metaphorically) ask revenge if the ruler were to step down. Furthermore, since the number of misdeeds and of rulers’ real or imagined enemies multiplies with each additional year in power, rulers need to resort to increasingly greater oppression to stay in power. Thus, even the originally well-meaning or tolerant rulers become, with the duration of their rule, tyrants. Basu is aware of the millennial nature of the problem; he cites Shakespeare’s Macbeth. He could have also cited Tacitus’ description of Tiberius’ descent into murderous suspiciousness and folly.