As Poland’s Senate passed what The New York Times editorial page called “a needless, foolish and insulting draft bill that would penalize any suggestion of complicity by the Polish state or the Polish nation in the Nazi death machine,” the National Library of Israel announced that it had received an astonishing donation that proved just how much everyday Poles knew about what was happening.

The evidence?

Envelopes.

The library announced that it had received a treasure trove of 59 envelopes stored in a faded album. All the envelopes were mailed between September 1940 and May 1941 from the central office of a Jewish aid society in Krakow to branches of the Jewish aid society located throughout Poland.

The envelopes were returned to the sender, and all were marked with statements in Polish — written by hand by the mailmen—indicating exactly what happened to Poland’s Jews.

Statements on the letters include:

“Left this address.”

“The Jews were expelled.”

“The Jewish society no longer exists.”

If the mail carriers knew, and the Polish mail service knew, well, then, so did plenty of regular Poles. Three million Polish Jews perished in the Holocaust, approximately ten percent of the country’s population. Over ninety percent of Poland’s Jews were murdered.

It’s the kind of population change that mailmen notice.

Poland’s Senate passed the amendment late at night. The vote was 57 to 23, with two abstentions. The language reads: “anyone, against the facts, that publicly states that the Polish nation or state was responsible or co-responsible for Third Reich crimes… is punishable by up to three years in prison.”

But the envelopes now in the possession of the National Library of Israel have a way of talking back to that now-legal language. On the question of whether and how much Poles assisted Nazis in the extermination of Jews, the envelopes offer evidence. Some of the envelopes also had a mark — in Polish — saying “Victory to Germans on all fronts!”

Yosef Weichert, who donated the envelopes, is an engineer in Tel Aviv and the son of Dr. Michael Weichert, whose archive has been in the National Library of Israel for fifty years. Dr. Weichert, who was born in Galicia in 1890 and rose to an executive position in Poland’s Jewish community, had a very difficult job in the early years of the war. The aid society he ran was under the tight control of the Nazis, but the funding for the organization came from the Joint Distribution Committee in the U.S. It seems as if Weichert did what he could under unimaginable conditions.

According to the National Library of Israel blog, Dr. Weichert was devastated when he read the writing on the envelopes, because he knew it meant the destruction of an entire Jewish community. He also believed the writing calling for victory to Germany on all fronts indicated that plenty of Poles were assisting Nazis in their efforts to exterminate Poland’s Jews.

But still Dr. Weichert did what he could. The society, known in Polish as Żydowska Samopomoc Społeczna — ŻSS, distributed food to Jews and assisted Jews in forced-labor camps, among other duties. When the “Final Solution” was implemented, the society was closed; it was shut down on July 29, 1942, and instead the Gestapo ran an “office for Jews.”

That was it for the activities of Dr. Weichert.

After the war, Dr. Weichert was accused by Jews of collaborating with the Nazis and he and other leaders of the society spent years clearing their names. Dr. Weichert managed to hide evidence of what had happened to Poland’s Jews, and was able to retrieve his documentation after the war. Dr. Weichert donated almost everything to the National Library decades ago, but held on to the envelopes.

I can understand why. There is something very intimate about envelopes that reach an address but don’t reach the people who are supposed to be at that address. The envelopes reveal the thin line between life and death, truth and lie, everyday tasks like mail and the disruption of everything caused by genocide.

I had a deep personal reaction to the mailmen’s handwritten comments because my own grandfather received the packages he sent and letters he wrote to his family, trapped in Germany, years after the war ended. Scrawled back were the words: “Address unknown.”

The truth? Everyone was dead.

Murdered.

Only in the past several weeks did I learn that my grandfather’s four brothers and my great-grandparents were moved, by the Nazis, from one address to another in their home city of Bremen. The packages my grandfather sent, from Israel, were to the original address, where he grew up; the local mailmen knew more about his family’s fate than he did.

Clearly, the mailmen of Germany and Poland knew that longtime residents were no longer in their homes. But the donation received by the National Library of Israel proves that Poland’s mailmen, at least, knew more than that; writing that the Jews were expelled on an envelope, means a bit more than just knowing that someone has moved.

It’s not your standard change-of-address sticker.

The envelopes are one form of written history, but we are witnessing another. We are living in a moment in which world leaders are rewriting history — and using law to redefine truth. When Polish President Andrzej Duda claims — without shame — that Poland has the right “to defend historical truth,” everyone with an actual knowledge of history and an actual respect for truth should sit up and notice.

Using law to rewrite history has its own ugly history.

It is up to all of us, speakers of various languages, to insist that the words “history” and “truth” retain their meanings. We must read the writing on the envelopes, and we must do everything we can — as Yosef Weichert did — to make historical evidence available to the public. The truth can vanish quickly, as Poland demonstrated this week, with the action taking place in a swift vote, late at night. Next time, there may not be any paper envelopes to refute the lies.

Aviya Kushner is The Forward’ s language columnist and the author of The Grammar of God (Spiegel & Grau). Follow her on Twitter @AviyaKushner