Tom McNichol, a frequent contributor to TheAtlantic.com, is a San Francisco writer whose work has also appeared in the New Yorker, the New York Times, the Washington Post, and on NPR's "All Things Considered."

Richard Nixon had some pretty strange moments as president -- an Oval Office meeting with Elvis Presley during which the pill-addled singer lobbied to be deputized as a federal agent-at-large in the War on Drugs; Nixon's declaration to a roomful of newspaper editors at the height of the Watergate scandal, "I am not a crook;" Nixon asking Henry Kissinger to kneel down and pray with him and then bursting into tears the night before he resigned.

But perhaps the most bizarre moment of the Nixon presidency took place in the early morning hours of May 9, 1970, during which Nixon, with his faithful White House butler in tow, made an impromptu visit to the Lincoln Memorial and engaged in a rambling dialogue with student protestors. The incident took place at a tumultuous time in the Nixon presidency, shortly after the invasion of Cambodia and the resulting explosion of outrage on college campuses, culminating in the killing of four students at Kent State University on May 4. Nixon's erratic behavior during the Lincoln Memorial visit would have even his closest aides wondering if the president was losing it. Nixon's Chief of Staff H. R. Haldeman would write in his diary hours after the Lincoln Memorial visit, "I am concerned about his condition," and note that Nixon's behavior that morning constituted "the weirdest day so far."

Last week, the Nixon Presidential Library and Museum opened formerly restricted materials from five Watergate-related transcripts of the Nixon White House tapes, plus a series of presidential dictabelts. Five of the dictabelt recordings feature Nixon dictating a memo to Haldeman that offers his version of the Lincoln Memorial incident. Details of Haldeman memo had surfaced before, but this marks the first time the public has heard Nixon recount the event in his own voice.

Nixon begins his dictated memo by instructing that his recollections of the Lincoln Memorial trip be distributed "on a very limited basis" to close aides and "anyone else who may have raised questions." From the start, it's clear that Nixon's memo is an attempt at damage control, aiming to counter the perception of his Lincoln Memorial sojourn. Details of the visit had already begun appearing in the press, hinting at an exhausted and overwrought president engaging students in nonsensical banter....