Even by the regular horrors of a brutal world, even by commonplace terrorist killings in Pakistan, even by terrorist standards, the slaughter of 132 children and nine staff at a Peshawar army school is monstrous and almost beyond belief.
How can fellow humans massacre children systematically and in cold blood, hunting them down and shooting most in the head even as they tried to hide under desks?
What depravity is in the human soul? This was not the act of a deranged or deluded individual but a specific and organised action by fanatics with a sick and warped ideology.
The Tehreek-e-Taliban Pakistan (TTP) has shown its heart is blacker than a terrorist flag.
It takes a lot to rock and shock Pakistan as this incident has done.
After all, 1000 schools have been targeted since 2009. Two years ago a Taliban member seriously wounded 14-year-old Malala Yousafzai on a school bus.
Terrorist violence deaths (including terrorists themselves) are estimated to total 5000 this year, and more than 40,000 since the September 11 attacks.
But these were not civilians killed in crossfire or even as hostages. The murderers specifically sought out children, most of whom were boys aged about 13 to 16.
Supposedly, last week's slayings at the army school were in revenge for Pakistan Army action in tribal areas and United States drone strikes against Taliban leaders.
For too long Pakistan has prevaricated on decisive action against the Taliban.
Negotiations and appeasement and talk of ''good'' and ''bad'' Taliban have been seen as weakness and exploited. Too many in the security apparatus have used extremists when it suited their aims. Too many played both sides.
Fundamentally, though, the Taliban wants to overthrow the Government and bring its vision of society to fruition. Its fundamentalism does not allow room for any significant compromise.
It seems, though, that Pakistan's recent offensive against the Taliban has had an impact, and that might well have spurred the outrage. Groups were struggling to make much impact on military targets and instead resorted to attacking a school.
In the short term, Pakistan is united and the resolve against the Taliban and other Islamic extremists has firmed.
''We will wage a war till the time not a single terrorist is left in Pakistan,'' Pakistan Prime Minister Nawaz Sharif said on Wednesday.
Air strikes stepped up and, surely, the army will now go after the Taliban and especially the TTP with extra purpose. The ban on the death penalty has been lifted and political rivals have agreed to work together on a anti-terrorist plan.
What, though, will happen months ahead?
Will Pakistan revert to its old ways? Will it all become too messy and difficult? Or will the massacre provide an opportunity to strengthen the nation against those who would bring it down and also help underpin a more successful state?
Will it help foster a new era of co-operation with the United States and Afghanistan against terrorists?
Pakistan has wallowed in corruption, violence and misgovernment.
It has lived with extremist groups attacking minorities for many years. It, and its people, desperately need to disown rabid fundamentalism and endeavour to built a society that accepts pluralism.
Pakistan, a land with a population of about 182 million, has the world's sympathy in this outrage. Long-time foe India is among nations sharing the grief.
It is heartening two minutes' silence was marked across its schools.
Meanwhile, in Abu Dhabi, Pakistan and New Zealand continued its cricket series, even though Pakistan was in the midst of three days of mourning.
New Zealand was prepared to stand aside if that was the Pakistani wish, but it was decided the cricket would continue.
In a way, that is a positive approach. No matter the sheer horror of Peshawar and the more than 140 deaths, life for everyone else must go on.
