WASHINGTON -- Because John McCain and other legislators worry that they are easily corrupted, there are legal limits to the monetary contributions that anyone can make to political candidates. There are, however, no limits to the rhetorical contributions that the Rev. Jeremiah Wright can make to McCain's campaign.

Because Wright is a gift determined to keep on giving, this question arises: Can persons opposed to Barack Obama's candidacy justly make use of Wright's invariably interesting interventions in the campaign? The answer is: Certainly, because Wright's paranoias tell us something -- exactly what remains to be explored -- about his 20-year parishioner.

In Monday's speech at the National Press Club, Wright repeated -- decorously, by his standards, but clearly -- his accusation, made the Sunday after 9/11, that America got what it deserved. His Monday answer to a question about that accusation was: "Whatsoever you sow, that you also shall reap" and "you cannot do terrorism on other people and expect them never to come back on you."

As evidence that "our government is capable of doing anything," he strongly hinted that he has intellectually respectable corroboration -- he mentioned several publications -- for his original charge that the U.S. government is guilty of "inventing the HIV virus as a means of genocide against people of color." But on Monday he insisted that he is not anti-American: It is, he said, Americans' government, not the American public, that is a genocidal perpetrator of terrorism. So, he now denies that America has a representative government -- that it represents the public. He believes that elections constantly and mysteriously -- and against the public's will -- produce a genocidal, terroristic government.

On Monday, Wright also espoused the racialist doctrine that blacks have "different" learning styles than do others. This doctrine of racially different brains, or of an unalterably different black culture, is a doctrine today used to justify various soft bigotries of low expectations regarding blacks, and especially black children. It has a long pedigree as a rationalization for injustices. Slaveholders and, later, segregationists loved it.

Obama should be questioned about whether he agrees about "different" learning styles. It is, however, predictable that journalistic and political choruses will attempt to suppress such questioning by suggesting that it is somehow illegitimate. The "daisy ad" and "Willie Horton" will be darkly mentioned.

There have been two television ads in presidential campaigns concerning which there is a settled consensus of deep disapproval. In both cases, the consensus about these acts of supposed mischief is mistaken.

The first ad was used in 1964 by Lyndon Johnson against Barry Goldwater: A small girl plucked petals from a daisy as a voice counted down to a nuclear explosion. The ad, reflecting Johnson's fear that his large lead would cause complacency among his supporters, concluded with a voice saying: "The stakes are too high for you to stay home."

Goldwater and many of his supporters were incensed. But Goldwater had said several things suggestive of a somewhat cavalier attitude about the use of force, including nuclear weapons. He had made his judgment a legitimate issue.

In the spring of 1988, in a debate among candidates for the Democratic presidential nomination, Tennessee Sen. Al Gore used the matter of Willie Horton against Massachusetts Gov. Michael Dukakis, one of Gore's rivals. Horton had been in a Massachusetts prison serving a life sentence for the murder of a boy Horton stabbed 19 times during a robbery. Horton was frequently released on weekend furloughs. Finally, he fled, kidnapped a couple, stabbed the man and repeatedly raped the woman. Because the ad, made by supporters of Vice President George Bush, included a photo of Horton, critics called it racist. But supporters of Bush argued that the Horton episode was emblematic of Massachusetts' political culture, or of a liberal mentality, pertinent to assessing Dukakis.

When North Carolina Republicans recently ran an ad featuring Wright in full cry, McCain mounted his high horse, from which he rarely dismounts, and demanded that the ad be withdrawn. The North Carolinians properly refused. Wright is relevant.

He is a demagogue with whom Obama has had a voluntary 20-year relationship that implies, if not moral approval, certainly no serious disapproval. Wright also is an ongoing fountain of anti-American and, properly understood, anti-black rubbish. His Monday speech demonstrated that he wants to be a central figure in this presidential campaign. He should be.