A young John F. Kennedy filled dozens of pages in what historians believe to be his only diary. In one of the most interesting entries, Kennedy compares Adolf Hitler to a "legend."

After the fall of Nazi Germany in 1945, JFK visited Hitler’s bombed Bavarian Berghof residence and Eagle’s Nest mountain retreat.

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After the visit, which was part of his German tour as a Hearst newspaper war correspondent, a 28-year-old Kennedy wrote about his fascination with the dictator, who had just committed suicide four months prior to JFK’s visit.

“He had boundless ambition for his country which rendered him a menace to the peace of the world, but he had a mystery about him in the way he lived and in the manner of his death that will live and grow after him,” he wrote. “He had in him the stuff of which legends are made.”

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Kennedy predicted in his diary that Hitler would “emerge from the hatred that surrounds him now as one of the most significant figures who ever lived.”

The diary is set to be auctioned on April 26 at RR Auction in Boston by Deirdre Henderson, who was JFK’s research assistant when he was a Massachusetts senator.

Kennedy gave Henderson the diary so that she would be informed about his views on foreign policy issues and national security. She addresses his thoughts on Hitler in the auction description.

“When JFK said that Hitler ‘had in him the stuff of which legends are made,’ he was speaking to the mystery surrounding him, not the evil he demonstrated to the world,” she says. “Nowhere in this diary, or in any of his writings, is there any indication of sympathy for Nazi crimes or cause.”

Henderson told People that Kennedy’s interest in Hitler’s legacy could be credited to his education and his lifelong interest in history. She says he was doing his historical research even at the age of 12, when he was reading Churchill’s memoirs of World War I.

“It’s the mystery surrounding Hitler – why did he do what he did? I don’t think anyone will ever know,” she said. “But JFK was analyzing it and saying Hitler was a legend – and Hitler is a legend. But he’s not a good legend. You can’t translate that as meaning he had admiration for him.”

She intends to auction the original manuscript in honor of what would have been Kennedy’s 100th birthday on May 29.

“It’s part of his legacy.”