FOR THOSE WHO aren't historians, whether by profession or amateurish inclination, the mercuriality of historical reputation can be disconcerting. Surely, says the historical literalist, a great figure like Martin Luther, the principal architect of the sixteenth-century Protestant Reformation, was who he was, has been so from the first, and inquiry into his life and work is an incremental process. We simply accumulate facts until the inventory is complete. All the portrait will need after that is an occasional retouching as a stray fact comes to light. And you can say the same of other epochal figures--Julius Caesar, Henry VIII, Abraham Lincoln, or who you will.
As interested readers began to learn in 1983, during the five hundredth anniversary of Martin Luther's birth, the case of the great reformer proves the instability of historical portraiture. Like the secreted portrait of Oscar Wilde's Dorian Gray (though without intimations of corruption), it had been changing, while the conventional figure remains the same. Heiko Oberman recently trans