Just something to look out for...
The good aspect of Leftism is its kindness, and its loathing of cruelty. This is a virtue.
Of course, any virtue taken on its own or to excess becomes a vice, and this happens with Leftism - nonetheless kindness is a virtue.
Watch out, therefore, when Leftists - whether individually or institutionally - become sadistic!
When Leftists take pleasure, delight in the suffering of others - suffering of any others whether they 'deserve' it or not, whether they 'consent' to it or not - then this is terminal Leftism.
This happens when Leftism has served its purpose, and a person or society has moved to the next level of corruption; when good motive such as kindness can be dispensed-with and evil motives such as delight in cruelty from reasons of pride of sensuality move to the fore.
When hypocrisy is cast aside, and naked power is wielded with delight in overcoming, in crushing all opposition - that is a very dangerous shift in Leftism.
Even when sadism is disguised by the pseudo-impersonality and inexorability of bureaucratic procedure, it is usually easy enough to observe. There is, after all, a clear distinction between polar opposites such as kindness and sadism - even if the sadism is masked.
As an example think of Leftism and sex.
Leftism began as a compassionate and 'therapeutic' plea to allow various forbidden sexual practices to alleviate the suffering of those denied them; but has evolved into something very obviously hard and cruel - a strident set of demands, an advocacy of openly exploitative sex (sex as a tool of hedonism, sex as a vampiric extraction of motivation and meaning in life), sex as the basis of personal identity, and the clearly sadistic use of sexual ideology to justify hatred and the crushing of opponents.
When the Left discards kindness and embraces sadism - then it approaches more closely to pure evil. Almost anything becomes possible and excusable.
[Note: there is often an even more obvious 'Nietzschian' sadism among the type of Leftism which goes by the name Libertarianism or the secular right - indeed, one can often observe people (usually young men, sometimes disillusioned older men) actually trying to train themselves into cruel indifference; to expunge their natural kindness and sympathy.]