How do we comprehend this savagery against someone so conscientious and unifying?
Especially if it becomes contextualised in an otherwise "valid" politics of division and anger.
The sheer incomprehensibility shocks us into an overdue awakening.
Jarringly, we learn that threats of rape and murder against our elected representatives are endemic, and that there are people among us who act this way.
These are anti-democrats, morally adrift, politically deracinated, dangerous. Are they new or were they always there?
The Minister for Multicultural Affairs Anne Aly reports 19 death threats in the past week alone.
Someone laments via social media on Monday, (that is, before the attack on Helen Haines) that "not enough politicians are afraid for their lives right now," reports Nine's Jacqueline Maley.
Another aggressor observes, in the hours after, that Senator Jacqui Lambie - the subject of a vile One Nation attack - needs to meet a LandCruiser, reports Tanya Plibersek.
Every MP and senator experiences this, but women are vastly more targeted. This is a technologically enabled misogyny, a terrorism where hatred meets impulse. But who would do such a thing? Surely nobody we know, right?
We assume we are all equally appalled but cannot now unknow that some feel differently.
Our social democratic settlement is listing, beset by a variety of forces, not least of which is that we stopped strengthening it decades ago.
Renovation is urgent. Our leaders behaved as if democracy was a self-expressing, self-renewing, self-legitimising machine. That it was girded by rules, fixed players, agreed norms, even as their parties gamed it to death by ignoring safe seat voters - their own and their opponents'.
The key to the whole thing was that voters recognised the legitimacy of the government even if personally they had not voted for it.
Now, in the face of pernicious new inputs like foreign-controlled social media, the social licence for a responsive form of legitimate government is being withdrawn.
Violence and the spectre of it looms. Australia is not a country of brutality-worship like the US. We haven't elevated gun ownership over life itself, and we don't stage blood-sports on the lawns of The Lodge.
We are better but we cannot be complacent.
As academics, Bongiorno and Black observed this week, "democracy is a practice as much as a system". Its defence requires more than trite praise for the Australian marvel of compulsory preferential voting and an independent electoral commission. It must be lived, animated, taught, practised.
There are multiple worthy options including genuine national civics education, deliberative assemblies and citizens juries on contentious issues, fixed four-year federal terms, and optional 16- to 18-year-old voting.
Meanwhile, the public square has surrendered to pitched battle, vaulting incivility. Harsh words eclipse reasoned argument.
Even those of us in the communicating business experience a gnawing impotence - the harder we try, the more our invocations fall short.
Grasping for clues, a weak consensus forms behind Anthony Albanese's vague entreaty - and that of ASIO boss Mike Burgess - to "lower the temperature". It seems right, this proposition that the febrile tone of public discourse had been, if not causal, then in some way facilitative.
But what does it mean and how is it achieved?
Nobody knows. This, like all the other attempts at finger-pointing leads us everywhere and nowhere.
Situating this vile incident within the zeitgeist invites this categorisation dilemma - a confusion of specific-versus-general illuminating nothing.
Critically, the deranged impetus of Wangaratta remains unclear. Is it political extremism, a family property dispute or a mental health episode? It's as if these cannot co-exist or unduly magnify each other.
That the normalisation of aggression and abuse in political dealings may itself be another symptom is acknowledged but left largely uninterrogated. Partly, because it is unprovable.
While the criminal justice system begins a tightly defined prosecution, the ailing political system, its lower evidentiary standards already satisfied, ponders a wider soul-searching.
But where to start? The antisocial wilds of social media? Parliamentary raucousness and the daily disrespect emanating from Capital Hill? Or mainstream media cynicism and the vomitus indignations of partisan foghorns for whom outrage is bankable.
What is clear is that in what was the world's model liberal democracy, the case against a negligent political class seems strong.
Ignoring this, we comfort ourselves with terms like turning point, wake-up call, watershed, and make well-intentioned predictions about the longer-term implications of this terrible moment.
Experience tells a less optimistic story. Britain's political class was rocked by the stabbing murder of Labour MP Jo Cox in 2016 and vowed to lift its standards, be kinder, behave more responsibly.
Like Tony Abbott's "kinder gentler polity", these fine intentions were quickly forgotten. Two more political figures have been killed since.
Kim Leadbeater, the sister of the late Jo Cox is now herself an MP. Speaking on Australian media this week she noted a certain repetitive theme when attacks occur.
Politicians and media proprietors commit to a more respectful, less personalised comportment. And to be fair, most mean it.
But as Leadbeater told Sarah Ferguson, while the families and friends carry the trauma in their hearts and recall it every day, the rest of us go back to our own lives, to new problems and, regrettably, old habits.