President Reagan, in the loss of one friend and serious illness of another, has had new reminders of his own mortality. So have all of us who knew Federal Maritime Commission Chairman Ed Hickey, a former Secret Service agent and White House aide, who died of a heart attack at age 52.

Hickey could have been Vince Lombardi's idea of a cop. Like Lombardi, he believed in God, country, family and team. He was a devout Roman Catholic and patriotic Irish American afflicted by the useful delusion that St. Patrick's Day was a national holiday. His family was his wife, Barbara, and their seven sons, ages 17 to 27. "I think I have Ed in all seven of them, and it helps me a lot," she said after the funeral last Wednesday.

Hickey's team was Ronald Reagan. They met in 1968 when Hickey was a member of the Secret Service detail assigned to protect Reagan, then California governor and an undeclared presidential candidate. The protection was ordered by President Lyndon B. Johnson the day after Sen. Robert F. Kennedy (D-N.Y.) won the California presidential primary and was assassinated. It was withdrawn after the Republicans nominated Richard M. Nixon. By then, Reagan, who is close to few people other than his wife, Nancy, had formed a lifetime friendship with Hickey.

Some months later, Reagan was in Boston campaigning for the Republican ticket while a noisy demonstration raged outside his hotel. In those days, Reagan always called Hickey "Boston Blackie" because of a supposed resemblance to the late Kent Taylor, a dapper, crime-stopping detective in a 1950s television series. For some reason, Reagan's aides were especially worried about the demonstrators that evening, and the Boston-based Hickey came over to see Reagan. "Boston Blackie," Reagan yelled when he saw Hickey in the hotel lobby, giving him an uncharacteristic hug. Reagan then assured members of his concerned entourage that they had nothing to fear.

Hickey quit the Secret Service the following year and went to Sacramento to direct personal security for the Reagans. He was working in London as a State Department security officer when Reagan was elected president in 1980. Some of Hickey's London colleagues were skeptical about his stories of his friendship with Reagan, but the skepticism vanished the day after the election when a cable issued at the president-elect's request directed Hickey to return to Washington as a member of the transition team. Reagan, talking to aides in his suite after the election returns came in, said to them, "Okay, you guys, where's Hickey?"

Reagan issued a statement calling Hickey's death "the tragic loss of a valued friend." He telephoned Barbara Hickey to talk about their loss. It was a difficult conversation for both, but Reagan is becoming accustomed to painful telephone calls. Last month, he initiated a call to Bill Roberts, his first campaign manager, who is recovering in a Los Angeles hospital from diabetes, which required amputation of one leg, then the other.

Roberts, a gritty politician who did much in 1966 to dispel the stereotype that Reagan was an unelectable right-wing actor, has been on the outs since he helped President Gerald R. Ford derail Reagan's challenge in 1976. Never one to mince words, Roberts at the time described Reagan as a "figurehead" who was "totally unqualified to be president." When Roberts was told that Reagan was calling him in the hospital, he thought it was a gag perpetrated by his public relations partners. But the caller was indeed the president, who talked for 15 minutes and tried to encourage Roberts by telling him about the achievements of athletes with artificial limbs. "It was," Roberts said, "a very gracious thing for him to do."

I last saw Hickey a month ago at Laurel Race Course where we bet on the same losing horse, and he bragged about his family. I saw Roberts this month at the hospital, where he reminisced about the old days and told about the phone call from the president. Roberts had been fitted with his second artificial leg that day and had walked 35 steps. "I'm going to walk out of this hospital on these," he said, patting the new leg. His longtime friends, including the president, are rooting for him.

Reaganism of the Week: Defending his conduct in the Iran-contra affair, while answering questions in Cleveland last Monday, the president said, "I would have to say that, in all the investigation that went on, I did not see any of what I considered lawbreaking that was taking place on the part of anyone in the administration."