Those who cannot remember the past are condemned to repeat it.

George Santayana wrote that sentence in 1905 but never in American history has it been more important. As control of Congress, the Supreme Court, the Mueller investigation and the Trump presidency all hang in the balance, we badly need to remember. The current firestorm surrounding Rod Rosenstein, the deputy attorney general to whom Mueller reports, is just the latest of many reminders of Watergate.

Between June 1972 and September 1974, as a result of the Watergate scandal, America’s constitution, institutions and national moral fiber were tested as never before, in ways terrifyingly reminiscent of what we face now. While our system did not perform perfectly, it performed quite well. Evil was exposed, bad guys (and they were all guys) were punished, a president was forced from office. There were no wars, no coups, no systemic meltdown.

But after spending two years intensively studying Watergate in order to make a four-and-a-half-hour-long film and miniseries about it, I have reached a number of conclusions, some of them less than totally reassuring with regard to our current situation.

First, the successful resolution of Watergate depended heavily on the immense courage, determination and principle of two-dozen individuals who went far beyond the obligations of their job descriptions, sometimes at great personal risk. (Interestingly, a strikingly high proportion of those people were very young, female or both.) Nixon initially succeeded in keeping the Watergate case under political control. So, what would have happened if Woodward and Bernstein hadn’t been so totally determined? When Richard Nixon’s Committee to Re-elect the President shut them out, they got a phone directory from an ex-girlfriend and started visiting dozens of people at home, at night, ultimately interviewing hundreds. Nixon’s gang smeared and threatened them; they didn’t back down.

And what if the owner of the Washington Post, Katharine Graham, hadn’t possessed a spinal cord of tempered steel? When the Committee to Re-Elect the President filed a lawsuit in order to subpoena Woodward and Bernstein’s notes, her response was: Those aren’t their notes. They’re my notes. And if anyone’s going to jail, it’s going to be me. Then Nixon went after her television licenses—but she didn’t back down either. And there was Judge John J. Sirica, who smelled a rat when the original Watergate prosecutors wouldn’t go after the Nixon White House. Sirica told the burglars that he’d jail them for life unless they talked.

Second, in the Watergate case, the courage of individuals was magnified by the general culture of serious purpose, and considerable bipartisanship (or non-partisanship) that infused the entire federal government. By a vote of 77-0, the Senate created a special committee to investigate. Then Congress forced Nixon’s attorney general, Elliott Richardson, to appoint a special prosecutor, Archibald Cox. Cox took his job seriously and got too close, so Nixon ordered Richardson to fire Cox. Richardson refused, and resigned instead. Then Nixon ordered Deputy Attorney General William Ruckelshaus to fire Cox. Ruckelshaus refused too, so Nixon fired him. Finally the Justice Department’s number three, Robert Bork, did Nixon’s wetwork, firing Cox and ordering the FBI to occupy Cox’s offices.

But the “Saturday Night Massacre,” reported on live television, triggered the fury of the American people, which in turn led to impeachment proceedings, the appointment of a replacement special prosecutor, and a Supreme Court confrontation. Moreover, Cox’s young assistant prosecutors had civil service protection, so they were hard to fire, and they soldiered on, with great courage. The House Judiciary Committee voted overwhelmingly, with considerable Republican support, to send three impeachment resolutions to the full House of Representatives. The Supreme Court, which included three Nixon appointees, unanimously ruled that Nixon had to surrender his secret Oval Office tape recordings to the special prosecutor, which doomed him.

Faced with certain impeachment and conviction, Nixon resigned. But to his credit, Nixon cared about the presidency and the verdict of history. He did not pardon himself or any of his co-conspirators—although he was soon pardoned by President Gerald Ford.

But now, back to Rosenstein and Mueller. Watergate led to a law protecting special prosecutors. It was flawed, but instead of fixing it, it was allowed to lapse completely in 1999. So Mueller is hanging by the thread of Rosenstein’s support—not of legal guarantees. We are very lucky that Rosenstein seems to be a tough, principled man. But how long will he last? And if Trump fires Rosenstein and Mueller, would we see the same firestorm as we did in 1973? Would the Supreme Court support the rule of law in the same way, particularly with Brett Kavanaugh on the bench? Would Congress start impeachment proceedings, especially if it remains under Republican control? Could a sufficiently bipartisan consensus ever emerge in the Senate for the two-thirds majority required for conviction and removal from office?

I confess that I do not feel confidence that the same things would occur now. Congress is a different creature than in 1973. Obviously it is enormously more partisan, but just as disturbingly, it is just a ticket to stamp on the way to a high-income lobbying career. The caliber of members suffers accordingly. The Supreme Court is different, too—more partisan, more ideological, more divided. And with Brett Kavanaugh confirmed, it contains two justices who have plausibly been accused of sexual harassment.

What do we conclude? For one thing, the independence of our institutions from political pressure—the FBI, the Department of Justice, the Supreme Court, the media—has never been more important. And for another, it matters who is in Congress—and who sits on the Supreme Court. Over the next few months, we might find out just how much. And we would do well to look again at how important those things were, once upon a time.

‘Watergate’ opens in Los Angeles on Oct. 19 and will air on the History Channel Nov. 2-4 .