The full history of the United States, given the secretiveness of government officials, has never been told. Many of the nation's most fascinating historical documents are still classified, under lock in an unusual library -- the "Historical Intelligence Collection," maintained by the Central Intelligenc Agency.

The hoary documents, some of which date back nearly 200 years, are available to properly cleared researchers who want to dress up their learned reports. But not a whisper of this classified history is released to the public. It appears only in "Studies in Intelligence," a secret-in-house CIA journal published on an irregular basis.

There's a lingering suspicion that many of the documents in the collection are copies of publicly available material in the National Archieves. But the CIA still won't let anyone look at the stuff without security clearance. t

Lifting the agency's veil of secrecy a millimeter or two, a CIA spokesman acknowledged that the library does exist. But he absolutely refused to let my associate Dale Van Atta see any of the memorabilia in the collection. Nor would the official permit an interview with the curator or anyone connected with the library.

The absurdity of the CIA's obsessive secrecy can best be illustrated by citing examples of the library's material, which I obtained from unofficial sources.

One choice item is a note dated May 27, 1793, from then-Secretary of State Thomas Jefferson to a fellow Virginian, James Madison, who was serving in the House of Representatives. Jefferson wanted to recruit a spy to operate in the French-owned territory of Louisana.

"We want an intelligent and prudent native," he wrote, "who will go to reside in New Orleans as a secret correspondent for 1,000 dollars a year. He might do a little business, merely to cover his real office. Do point out such a one."

Jefferson then added a telling observation on the residents of his native state. "Virginia," he wrote, "ought to offer more loungers equal to this, and ready for it, than any other state."

Another document is an agenccy historian's chronicle of President Franklin Pierce's opposition to a 19th-century Bay of Pigs operation. When he was inaugurated in 1853, "Pierce hoped -- like many Americans -- that the Cuban people would revolt and, like Texas, seek admission to the Union as a state, [though] political reality dictated otherwise," the researcher wrote. "Acquisition of Cuba from Spain, he decided, must be peaceable means, if at all."

The secret document continues: "One problem facing Pierce was a filabustering expedition against Cuba by his old wartime colleague, Brig. Gen. John Anthony Quitman. Quitman, working with a Cuban junta, sought to 'free Cuba.' Pierce opted to disclose intelligence to Quitman in an effort to discourage the move." An unclassified Pierce biography discloses that Quitman was shown the intelligence report on Cuban fortifications, "realized the he could not succeed, and quit."

Other material in the CIA library includes an account of secret codes and ciphers used in the Revolutionary War. Presumably the codes are not still in use at the Pentagon, but the spy agency keeps them locked up anyway.

John Jay, who would become the first chief justice of the United States, was the rebels' chief of counterintelligence. As such, the secret research shows, he "devised a code which used a dictionary as a code book, and a simple substitution chart for names and words not in the dictionary."

Another prominent Founding Father, Robert Morris, devised a different code. He was a member of both the Committee of Secret Correspondence (foreign intelligence) and the Secret Committee (covert procurement) of the Continental Congress. Morris' code was to be used in communicating with the commander in chief, George Washington, also known as "711." One example is a message from Abraham Woodhull ("722") to 711: "Dqpeu Beyocpu [Jonas Hawkins] agreeable to 28 [recruitment] . . ."

The secret history reports that James Lovell, who was the Secret Committee's crytographer for communications with its agents abroad, was arrested and imprisoned by the British as a suspected spy after the Battle of Bunker Hill. The nonpareil cryptographer of the Revolution, however, was Charles Dumas, who operated at the Hague. His code, the CIA researcher notes, "was pronounced unbreakable by the British, who intercepted some of his dispatches."

One vignette the CIA evidently fears the Soviets might use to undermine Franco-American relations concerns the Marquis de Lafayette's self-confessed difficulty with secret codes. In the postscript of a message to the counte d'Estaing, the young nobleman wrote: "I beg you to excuse the awkwardness and the bad construction of my ciphers; I am very new at this business, and I fear I have made them as unintelligible to you as they would be to My Lord Howe."