George H.W. Bush loved the CIA. It was “part of my heartbeat,” he once said. He was the only president who ever ran the agency, and the last president who truly believed in its Cold War code: Admit nothing, deny everything.

The wall of silence cracked during the administration of Bush’s successor, Bill Clinton, when the FBI’s arrest of Aldrich Ames, a Russian mole who went undetected by the CIA for nine years, led the agency’s directors to denounce systemic flaws in the CIA’s integrity. The wall crumbled when the 9/11 Commission disclosed the CIA’s dead-wrong reporting on weapons of mass destruction in Iraq, a false case for a brutal war led by Bush’s son. By the time reporters brought to light the CIA’s secret prisons and its torture of terrorism suspects — the torture authorized by that son — the wall was dust.

Everything we know about the late president suggests that he might have been privately appalled by these failures of common law and common sense. But he never said anything — not in public. The CIA was his spy service, right or wrong. He protected it at all costs.

In his last days as president, in 1992, he pardoned the convicted chief of the CIA’s clandestine service, protecting him from five years in prison in the aftermath of the Reagan administration’s greatest scandal, the Iran-contra imbroglio. He swept away three more guilty pleas and two pending trials in the investigation — among the defendants were two other senior CIA officials — including a case in which he would have been a material witness.

With that, Lawrence E. Walsh, the independent prosecutor investigating the scandal, declared that “the Iran-contra cover-up … has now been completed.” Walsh went on to say that Bush’s decision “undermines the principle that no man is above the law. It demonstrates that powerful people with powerful allies can commit serious crimes in high office — deliberately abusing the public trust without consequence.”

In January 1976, when Bush first arrived at the CIA headquarters in Langley, Va., that now bears his name, the CIA was being sacked like a conquered city. A quarter-century’s worth of dirty secrets were starting to spill as Congress combed through its files following Watergate and the revelation that the CIA had spied on Americans in violation of its charter. President Gerald Ford appointed Bush as part of a shake-up in his administration at the end of 1975, in which Donald H. Rumsfeld became defense secretary and Richard B. Cheney took Rumsfeld’s place as White House chief of staff.

Bush had been a two-term congressman and the chairman of the Republican National Committee, defending Richard Nixon during the worst of Watergate. He was the first career politician ever named to run the CIA — his predecessors were intelligence professionals, generals and admirals — and he worried that it would be the finish of his ambitions.

“I see this as the total end of any political future,” he told Ford. But he was thrilled running the agency. The secrets, the gadgets, the intrigue, the brotherhood — the CIA was like his old Yale secret society Skull and Bones, with a billion-dollar budget. “This is the most interesting job I’ve ever had,” he wrote to a friend in March 1976.

It was a terrible time for the nation’s spies. Bush spent much of his energies during his 11 months as director battling senators coming to the conclusion of their year-long investigation of the CIA. They uncovered the existence of assassination plots, secret wars, antidemocratic coups and mind-control experiments using LSD on unwitting human guinea pigs. Bush decried these revelations — not the facts revealed — saying “they devastated the morale of perhaps the finest group of public servants this country has.”

Bush implored Ford to shield the CIA from Congress, to little avail. Ford and Secretary of State Henry Kissinger had ordered the CIA to ship $48 million in money and weapons to guerrillas in Angola aligned with South Africa’s apartheid regime. Congress, previously ill informed about current covert operations, caught wind of the program and killed it. At a National Security Council meeting, Kissinger commiserated with Bush over the assault on the CIA’s covert actions. “Henry, you are right,” Bush replied, in a rare critique. “We are both ineffective and scared.”

Two weeks after Jimmy Carter was elected president in November 1976, Bush flew down to Plains, Ga., in a CIA aircraft to brief him — and politely pleaded for his job.

“Bush wanted to be kept on” as director of central intelligence, Carter later recalled with a laugh. “If I had agreed to that, he never would have become president. His career would have gone off on a whole different track!” Bush’s memo of the meeting shows that he briefed the president-elect on deep secrets, including the CIA’s financial support for foreign rulers and strongmen such as Manuel Antonio Noriega, the future dictator of Panama. He noted that Carter was “a little turned off. He tended to moralize.”

In 1989, more than a dozen years after that meeting with Carter, the newly inaugurated President Bush instructed the CIA to overthrow Gen. Noriega, authorizing three covert actions, including paramilitary support for a coup. Longtime clandestine service officers, including the station chief in Panama, were reluctant at best and resistant at worst. When the CIA balked, Bush unleashed the biggest American military operation since the Vietnam War to depose Noriega and arrest him on cocaine-trafficking charges. Twenty-three Americans and hundreds of Panamanian civilians died. He was privately — never publicly — furious at the CIA’s failure to overthrow Noriega in secret.

And he never remarked on the inability of spies and analysts to foresee the collapse of the United States' main enemy. “They talked about the Soviet Union as if they weren’t reading the newspapers, much less developed clandestine intelligence,” said Adm. William J. Crowe Jr., chairman of the Joint Chiefs of Staff under Bush.

The CIA has evolved in the quarter-century since Bush left office. More officers speak Arabic and Chinese. Fewer live in a mystical political and cultural bubble out in the Virginia woods, apart and aloof from the mainstream of American society. The spies and the analysts are more diverse than they were in the 20th century. The agency looks more like America than it used to. We don’t have to share Bush’s devotion to the CIA to understand that a nation with soldiers deployed all over the world needs a civilian intelligence service to look over the horizon and to try to anticipate surprise.

What might Bush have thought of President Trump’s denouncing the CIA’s officers as Nazis? Or the terrible idea that Trump might be a danger to national security? Several of his successors as CIA directors — John O. Brennan and Michael V. Hayden among them — have broken the code of silence. They have warned us that Trump presents an intelligence nightmare. But we’ll never know what Bush might say. He has taken that secret to the grave.