I guess she means he left communism. A belief in history, almost as a god, is inherent in communism as I understand it. The changes they believe in are pre-ordained, they need only to join the stream.
Please don't take HN threads on generic ideological tangents. The topic is Auden, not another litany about communism, and I'm sure Arendt meant something more subtle than that.
If you read the article, it's clear that "leaving the train of history" refers both to abandoning communism and to not subsequently "changing train" to another 20th C ideology (capitalism/Freudianism/refined Marxism), instead choosing to subscribe to Christianity (understood as a conservative orthodoxy).
So you're right about the association of historicism/Whig history with communism, but for Arendt that category (historicist ideologies) didn't just include communism.
This doesn't make sense for various reasons, to me, but people's understanding of communism varies (I'm a Marxist). For one, both the belief in the History and the History comes after the very reality that makes history possible, and we construct History only after we look at the facts and analyze them. Thus, belief in History as if it's not a "moving target" (so to say) presupposes History before material grounds that generates history and thus is idealistic (so it's not Marxist). Second, Marxism is more about understanding the History and explaining mechanisms that make certain transitions (like social class or economic system) possible, like a physicist explains the universe, rather than fixing an understanding of the History and working from there (which is very problematic from a empiricist point of view). This can be contrasted with other understandings of "socialism" most importantly Anarchism which starts from a ground truth that originates from morality (e.g. it is bad to kill people).
Communism does not have the pretensions to divinity and supernatural aspects that we see manifested during elections in the USA.
It has a recognition that the forces of production change. That relations of production change, and this base changes superstructure in the society. Hunter gatherer tribes make way for Sumerian and Greek slave empires, make way for feudal Europe, which make way for capitalism and bourgeois republics.
The Paris commune, the Russian revolution, the 1936 Spanish republic etc. are seen in this light as nascent proto-steps toward the next superstructure coming out of changed forces of production and relations of production.
History has already seen four major changes from one system to another, but not by means of divinity. Marx's pointed to contradictions inherent to capitalism. I think the 2008 bailout and crisis would be a sign of the eventual end in Marx's view - US Treasury secretary Hank Paulson said GE CEO Jeff Immelt visited him on September 15, 2008 and said GE was having trouble financing day-to-day operations. Events like that are harbingers of the eventual collapse of the capitalist economic system, in Marx's view. For now, the government and taxpayer bailing out the capitalists and corporations work, in Marx's view, one day it will not work. But the collapses are only part of the collapse, advances had to have happened to shift the system as well. It is not divinity, it is history continuing to be dialectic.
https://news.ycombinator.com/item?id=15367489
https://hn.algolia.com/?sort=byDate&dateRange=all&type=comme...