At the start of his campaign, Obama ran in counterpoint to the previous candidacies of Jesse Jackson and Al Sharpton. Here was a black man running for president on issues that had nothing to do with race as he rose above the victimization rhetoric that characterizes so many speeches of African-American political figures.

Now, in attacking the Rev. Wright as he did Tuesday, Obama can further define himself in contrast to Wright, just as he did earlier vis-à-vis Jackson and Sharpton.

So if, as the Chinese ideogram suggests, crisis is a synthesis of danger and opportunity, the controversy surrounding the Rev. Jeremiah Wright presents plenty of both for Obama.

In his statement Tuesday, Obama moved decisively and well to seize the opportunity that the Rev. Wright’s wrongs pose.

The danger Wright presents is obvious enough. Wright has come to epitomize everything white Americans fear in an African-American public figure, secular or clerical. He is anti-white, anti-American, and avidly embraces and propagates all manner of bizarre conspiracy theories. If he is to be believed, which is a very bad idea, the United States caused the AIDS virus in order to destroy the African-American population. The reality is the opposite: America took the lead in developing treatments for the disease, with the result being that a diagnosis of AIDS is no longer tantamount to a death sentence. Wright says that we give drugs to our children. Again, he is 180 degrees wide of the mark. We do more than any other nation to battle drugs and risk the lives of tens of thousands of noble and able DEA agents to keep them away from our children.

But if Wright has come to be the poster child for what America fears in a black public figure, he gives Obama an opportunity to be the opposite. By playing off Wright, by attacking his views in depth and detail, Obama can define himself as the un-Wright, reassuring Americans and carving out his identity in opposition to the reverend’s rantings. Obama has always implicitly defined himself as the opposite of Jesse Jackson and Al Sharpton. He runs not as a black man seeking the presidency, but as a post-racial political leader who happens to have a dark complexion. But that positioning is now obsolete in the face of the challenge Wright poses to his candidacy.

If Obama continued to base his defense on history, he will just wade into deeper trouble. The “I wasn’t there; I didn’t hear him” defense just invites journalists to interview thousands of members of the congregation to find one who sat next to Obama during one of Wright’s racist and anti-American sermons. Just as John Kerry let his candidacy be hostage to the memories of every GI who served alongside him in Vietnam, so Obama will tie his to the recollections of his co-parishioners.

Nor will Obama solve his Wright problem by subtly distancing himself from his pastor and condemning his views, in general, as “offensive” or “not representative of my campaign.”

Rather, he needs to seize the opportunity Wright presents and rebut the pastor’s views, point by point — as he began to do Tuesday — and, in the process, define himself and his candidacy. He needs to rebut all of the spurious points Wright raised in his now-famous “chickens coming home to roost” sermon and speak up for America, our record and our values. He needs to explain why we dropped the bomb on Hiroshima and Nagasaki — to save millions of American and Japanese lives, which would have been lost in an invasion. He should defend our support of Israel and take issue with Wright’s characterization of our backing for its efforts to protect itself as “terrorism.” He needs to speak out about America’s moral role in the world and differ sharply and publicly with Wright’s worldview.

By playing off Wright, he can recapture his identity as the personification of white hopes for a color-blind politics rather than white fears of anti-American and anti-white public figures.

The key to surviving the Wright challenge does not lie in the history of Obama’s 20-year involvement with his church. That story is a quagmire from which he will have difficulty extricating himself. The answer is, rather, to speak out in the here and now against Wright’s weekend comments in Washington and, thereby, tell us who he is and in what he believes.