THE OFFICIAL POSITION of China’s rulers is that the Tiananmen Square massacre of June 3-4, 1989, is not open for discussion: a student-led “counter-revolutionary rebellion” was put down by security forces. Case closed.

Yet, for an event so thoroughly airbrushed out of view, there was plenty of activity on its 23rd anniversary this week. A candlelight vigil in Hong Kong drew tens of thousands of people, one of the largest gatherings in that city since 1989. Authorities in a Beijing district posted stringent security precautions calling for “wartime systems and protective measures.” When the Shanghai stock market fell 64.89 points Monday — which some Chinese interpreted as an eerie reference to the date of the massacre — censors went into overdrive trying to wipe out any references to it on popular micro­blogs.

The memory of Tiananmen, in which hundreds and perhaps thousands of unarmed demonstators were killed, refuses to be extinguished, and tantalizing glimpses of the story have come from an unexpected quarter: former high-level party officials no longer willing to be silent. The latest to speak out is Chen Xitong, a hard-liner who was mayor of Beijing at the time and was later removed from office on corruption charges. Now 81 years old, battling cancer and presumably hoping to clear his reputation, Mr. Chen has given a series of interviews, published as a book in Hong Kong, in which he says the bloodshed was “of course a tragedy that could have been avoided and should have been avoided. . . . Nobody should have died if it had been handled properly.” Mr. Chen appears to be distancing himself from his report to the Standing Committee of the National People’s Congress just after the massacre, which said the crackdown was correct and unavoidable. Now, as The Post’s Andrew Higgins reported, Mr. Chen says he merely read out a script written for him by others in the party.

Zhao Ziyang, the reformist party general secretary who was forced out during Tiananmen and lived under house arrest until his death in 2005, secretly recorded audiotapes of his recollections. In 2009, the tapes were published in a memoir in which Mr. Zhao asserted (as he had at the time) that the Tiananmen student demonstrators were not seeking to overturn the party, and the proper response would have been to open a dialogue with them. Yet another trove of disclosures about the massacre came in documents purportedly from inside the party that were leaked and published abroad in 2001 as “The Tiananmen Papers.”

There will be more, and there are still plenty of unknowns, including how many people died. It’s reassuring to see some indications that Tiananmen hasn’t been entirely forgotten by Chinese, even if a younger generation has little exposure to the details. Ultimately, if China’s leaders are ever to contemplate a more democratic system, they must face the dark days of Tiananmen and provide a full accounting. But a party that maintains a monopoly on power will not easily relinquish a monopoly on history. The minute it does, a tightly wound ball of myths, justifications and coverups will begin to unravel.