Newsweek magazine, which nearly blew a wad of money on the "Hitler diaries," rather casually says at the end of its lengthy coverage that their genuineness "almost doesn't matter in the end." Real or fake, the excitement they generate tells us a lot about ourselves.

Newsweek may be right, though not quite in the sense intended. Real or fake, this "discovery" by Gerd Heidemann published in West Germany's Stern magazine is a fascinating parable of historical gullibility.

If I were teaching history I'd adjourn the topic of the day--what's the Donation of Constantine when so wonderful a case study is at hand?--and have my students tackle it as a living lesson in historical detection.

I'd begin with the amazing coincidence that these previously unheard-of handwritten diaries by the century's master villain (who dictated all his known writings, from "Mein Kampf" on) should appear on the 50th anniversary of Hitler's accession to power.

From there, I'd turn to its curious provenance: that a "former officer of the Wehrmacht" retrieved these notebooks, unscorched, from a flaming plane crash in 1945 and concealed them "in a hayloft" (where else, unless a pumpkin?) until his 81st year.

Now, Prussians are celebrated for self-discipline. But unless this unidentified old solider never heard of the rule of threescore- and-ten, or discovered the fountain of youth in his "comfortable country" of exile, how did he resist the temptation to fence this priceless treasure for so long? Abnormal self-restraint, even for a Prussian.

But these are only the most obvious puzzlers.

Consider next what has been disclosed about the physical condition of these "diaries." Here in mint condition are 60 identical notebooks, through which only some 50,000 words have been spaced. How many diaries covering 13 years are all written on the same materials? How many famous diarists (hang your head, Samuel Pepys) have been so thoughtful as to sign each page lest future readers doubt their authenticity. Hmmm.

And what about the familiar characters and episodes on which the "diaries" are said to shed light--or intriguing shadow?

Did Adolf Hitler really regard Neville Chamberlain, his hapless dupe at Munich, as "this smoothie Englishman . . . this cunning fox"? If so, that novel judgment was his alone. No stranger misconception has emerged since Malcolm Muggeridge's story that the Nazis, having read P. G. Wodehouse, sent spies to England in spats.

And speaking of the English--it is May 1940 and the Wehrmacht has the British Expeditionary Force pinned at Dunkirk-- they are, Hitler complains, "driving me crazy. Should I let them escape or not?"

Whoever wrote that knew that Dunkirk is a historical puzzler; that Hitler, to the dismay of his generals, ordered his armor to pause. But there is much authoritative testimony on the point. The terrain before Dunkirk was marshy and threaded with canals, unfriendly to tanks; and Hitler had been persuaded by Goering that the Luftwaffe could destroy the British forces on the beaches, sparing the army for the drive on Paris.

During the fateful pause, however, Goering's planes were foiled by bad weather and British Spitfires, while an armada of small craft ferried British and French armies across the Channel to safety. Like so many of history's puzzles, the Dunkirk miracle was made of muddle and miscalculation, not willed intent.

Even to one who has not examined the physical evidence, it seems overwhelmingly probable that the "diaries" are phony. That is apparently the almost universal suspicion of German scholars, whom Stern carefully kept out of the picture.

If they're forged, who benefits? Cupidity, of course, is never to be ruled out. But a palliated Hitler, a Hitler who admires Chamberlain, who can't bring himself to finish the British army at Dunkirk, who is even a secret co-conspirator in Rudolf Hess's crackpot "peace" mission to England, who says nothing revealing about genocide, has a role to play in creating discord within NATO. If, say, Eastern bloc forgers could make Hitler appear so "ordinary" and so reasonable, then the wartime Allies might seem malicious and unreasonable. Otherwise, why the crushing and division of Germany in 1944-45?

Good forgery is a bit like a chess board offensive. You must think at least one move ahead of the defender. The jury on the "Hitler diaries" is still out; but on the face of the matter it looks like clumsy chess to me.