With Mark Felt's surprise admission ending the decades-long search for "Deep Throat," scholars and pundits can now return to the still unsolved, century-old enigma posed by published revelations of an Abraham Lincoln confidante. Despite application of the latest high tech methods to determine authorship of The Diary of a Public Man, the source remains as shadowy as Hal Holbrook's character in All the President's Men.

Nothing comparable to "Deep Throat" occurred in the nearly two hundred years of presidential administrations preceding that of Richard Nixon. Although historians still debate whether Andrew Jackson really wrote the 1832 proclamation denouncing South Carolina's stand on nullification, authorship of a public document hardly compares with the disclosure of a fatal malignancy that brought down a president.

But long before Watergate the nation was shocked by the startling publication of The Diary of a Public Man. Appearing in serial form in the North American Review, the published diary ran in four monthly installments in late 1879. Carrying the enticing subtitle "Unpublished Passages of the Secret History of the American Civil War," the series aroused partisans of all sorts - Republicans, Democrats, secessionists and unionists - as it recounted the fateful events leading to civil war.

The diary seemingly contained inside information belatedly revealed by, in the words of the editor, "a public man intimately connected with the political movement of those dark and troubled times." The portions published by the Review covered the period from Dec. 28, 1860, until a few days after Lincoln's inauguration in March, 1861.

Although today's commentators argue over Felt's motive for finally coming forward, the editor of the Review thought it quite clear why the public man revealed the musings in his journal: "The author of it was actuated by a single desire to state things as they were...."

Names of several prominent participants in the tumultuous events that led to the secession of the Southern states are indicated in the published diary only by a dash, or an initial. While the diarist had written in the names, the Review editor worried about "wounding feelings which should be sacred." Therefore, "When men still living, but not now in the arena of politics, are referred to, it has been thought best to omit their names." By so doing, the editor made it harder to verify the conversations and to identify the author.

The "Public Man" was everywhere in Washington during those hectic weeks leading to Lincoln's inauguration, meeting with men of widely divergent opinions. He apparently knew everyone of significance in government and, with a seemingly unerring recall jotted down snatches of conversations in which he engaged. Public revelation of these conversations and the diarist's own comments about various national figures outraged readers still smarting from wounds of the Civil War. Numerous Lincoln anecdotes, some vigorously denied by historians, come from the diary.

Public revelation of these private conversations and the diarist's own comments about various national figures outraged readers still smarting from wounds of the Civil War. He criticized Major Robert Anderson and his officers for evacuating Fort Moultrie in the face of South Carolinian resistance, and gave credibility to the reported plot to kidnap President James Buchanan (which would have left Vice President John Breckenridge, a secessionist, as chief executive). Massachusetts Sen. Charles Sumner, idol of the abolitionists, received especial scorn, as did the Blair family, whose"mischievous influence" he denounced. General Winfield Scott appears as a doddering fool responsible for unnecessary military force displayed during the inauguration and for spreading rumors of plots against the president-elect. Even Lincoln's wife drew the"Public Man's" caustic criticism when he noted that her manners"were not those of a well-bred woman of the world."

Over the years identifying the author became a game in historical research. Henry Adams was an early nominee. Historian Frank Maloy Anderson, after devoting decades to an effort to identify the author, published in 1948 The Mystery of a Public Man: A Historical Detective Story, which suggested but could not prove definitively that Samuel Ward, brother of abolitionist Julia Howe Ward, was the secret author.

More recently two scholars from the College of New Jersey, Professors David Holmes and Daniel Crofts, applied the latest tools of stylometry for use in attributing authorship. They concluded after exhaustive comparisons with other contemporary diaries that the revelations were from the pen of William Henry Hurlbert, former editorial writer for the New York Times and later editor of the New York World. But despite his many connections with political leaders, Hurlbert was a secondary figure in 1860 and he may not have had the contacts recorded in the diary. Thus, despite their careful research, doubts about the authorship remain.

"Deep Throat," however, is no longer in dispute. Felt's unexpected revelation has aborted a hunt that already surpassed the search instigated by publication of the "Public Man's" diary. Historians and bloggers are now left with nothing more puzzling than who outed Valerie Plame.