THE SLAUGHTER of eight young yeshiva students and the wounding of nine others by an Arab terrorist in Jerusalem last week was a cold-blooded act of evil. It is difficult to make sense of the depraved fanaticism of someone like Ala Abu Dhaim, who calmly entered the school's busy library, took three guns from a box, and sprayed the room with hundreds of bullets before finally being shot dead by an off-duty military officer and a student who heard the gunfire and came running.

Even more perverse than Abu Dhaim's massacre, however, was the behavior that followed it.

In Gaza, the news that unarmed Jewish kids had been gunned down while at study set off paroxysms of joy. Thousands of jubilant Palestinians whooped it up in Gaza's streets, firing guns in the air to celebrate and distributing candy to passersby. Television cameras recorded the revelry; you can see it for yourself on YouTube.

Hamas, the terror organization that controls Gaza, issued a statement applauding the bloodshed. "We bless the [Jerusalem] operation," it said. "It will not be the last."

Give Hamas this much: It makes no secret of its bloodlust. The same cannot be said of Fatah, the other main faction in the Palestinian Authority. Fatah is headed by PA President Mahmoud Abbas, whose polished spokesman, Saeb Erekat, was quick to assure journalists - in English, for Western consumption - that Abbas "reiterated his condemnation of all attacks that target civilians, whether they are Palestinians or Israelis."

Yet just a few days before the yeshiva massacre, Abbas had told the Jordanian daily Al-Dustur - in Arabic, for Arab consumption - that he frowns on terrorist attacks only for tactical reasons "at this time" and that "in the future things may change." He boasted of his long involvement with PLO violence - "I had the honor of firing the first shot in 1965" - and claimed with pride that Fatah "taught resistance to everyone, including Hezbollah, who trained in our military camps."...