UNTIL RECENTLY few legacies seemed more unassailable than that of Helmut Kohl, the ex-chancellor who reunited Germany, wove it into the European Union, signed it onto the euro and kept his Christian Democratic Union comfortably in charge through 16 otherwise turbulent years. And few political reputations have disintegrated as rapidly and dramatically; a campaign finance scandal, greatly exacerbated by Mr. Kohl's inadequate response, has, in two months, engulfed him and his party. The scandal took a grisly turn yesterday when his party's longtime senior accountant committed suicide.

Word of irregularities in CDU financing seeped out just days after reunification's 10th anniversary, with reports that in 1991 the party treasurer, Walther Kiep, had accepted more than $600,000 in cash from a Canadian arms dealer. Mr. Kiep, under investigation for tax evasion, said the money had gone to the party. Mr. Kohl then admitted that he had accepted as much as $1 million in secret, off-the-books donations between 1993 and 1998--money he says went to party-building activities--and kept it in secret bank accounts.

Since then, despite the pleas of party leaders and the launching of criminal and parliamentary investigations, Mr. Kohl has refused to name the donors of this largess. When CDU leaders demanded that he choose between naming names and stepping down from his post as honorary chairman, he chose to step down; it was a matter, he told a Hamburg audience this week, of "my honor, as I understand it--others may understand it differently."

Others undoubtedly do--and should. Some CDU legislators now say Mr. Kohl should also resign his parliamentary seat, a step that would strip him of immunity and open him to more severe criminal penalties. The scandal, which daily grows in complexity and sums involved, raises some fundamental questions that can't yet be answered: Did postwar German stability, for example, depend on systemic corruption?

What is clear is that Mr. Kohl cannot halt the slide in his personal reputation without a prompt and full accounting, and that--more to the point--the German political system requires a rigorous inquiry into a scandal that is only beginning to take shape.