The other, darker "jihad" is the one that fits the prosecution's theory of this terror trial, one of armed struggle and the battle against infidels. One in which the quest for self-purification is waged by martyrdom, such as suicide bombings.

So which version of jihad is on the tapes played to the jury in the Yemeni Sheik's trial?

Yesterday, aided by Dr. Haykel, who has written about and lived in Yemen, the defense put forth an alternative way of considering those tapes. He described the sheik's world in Yemen as a place remote from the lives of the New York jurors, where words and gestures may have different meanings.

Under questioning from a defense lawyer, William H. Goodman, Dr. Haykel described a grindingly poor country, divided over terrorism, where there is wide support for Palestinians and great skepticism of America.

For every sinister implication from the prosecutors, he gave the defense another way of explaining things. Young men at a mass wedding held by the sheik had appeared militant by carrying swords, in a videotape shown to the jurors. But such swords, he said, were common ceremonial accessories in Yemeni weddings.

As to helping Hamas,

Dr. Haykel took a swipe, too, at the prosecutors' accusation that the sheik's friendly ties to Hamas were incriminating. "There are a billion plus Muslims in the Arab world, 90 percent of whom support Hamas," he testified. "If they were all terrorists, we would be in dire trouble

The Prosecution did elicit from Dr. Haykel that jihad can mean war.

In answer to a question, Dr. Haykel conceded that whatever people in Yemen may think of Hamas, it is a group that kills civilians and says there is no room for compromise with Israel.

"Now jihad, " Mr. Knox said, "in that context means 'war'?"

"Correct," Dr. Haykel said.

The point I think the defense is making is that there are two very different meanings of jihad: The one that applies to the globalized war of holy terror espoused by Osama bin Laden and al-Zarqawi --and a kinder, gentler, spiritual version. Apparently, both have existed side by side for more than 1,000 years.

This New York jury will have to decide which version of jihad the Yemeni Sheik was supporting and funding.