The day after Oct. 7. And the day after that.

Every victory brings with it the possibility of defeat.”

Every ending is a new beginning.

When we conclude each of the five books of the Torah (as we did last week) the reader leads the congregation in the refrain “chazak chazak v’nitchazek,” meaning “be strong, be strong, and let us be strengthened.”

This custom began in the 1100s, and is one of a group of customs related to finishing a Torah reading. According to Sephardic custom, after one receives an aliyah, congregants greet them with “chazak u’baruch, (may you be strong and blessed)”; Ashkenazi Jews say instead, “yiyasher kochacha (may your strength be renewed).”

After finishing an entire book of the Talmud, we read the siyum declaration which begins with the words “Hadran Alach (I will return to you),” expressing a commitment to return to that just studied. These customs declare that one can never retire from responsibility, even after extraordinary success. Endings are never the end.

For the same reason, on Simchat Torah, when we read the final Torah reading of the year, we go a step further and actually start reading the Torah again from the beginning. We want to make it clear we are not going to abandon the Torah, once completed. (Rabbi Joseph Ber Soloveitchik suggests that this may be why we say “Adon Olam” at the end of the Musaf prayer on Shabbat morning; even after lengthy service, we go right back to the very first prayer, indicating we are ready to start all over again!)

Every victory brings with it the possibility of defeat. Overconfidence can turn strong armies into weak ones. It is precisely after achieving success, after concluding the task, that we have to remember to “be strong, be strong, and be strengthened.”

One of the major British victories in World War II was the second Battle of El-Alamein, which ended on Nov. 11, 1942. That day, Winston Churchill spoke to Parliament to report on the victory. Then he added the following:

We are entitled to rejoice only upon the condition that we do not relax. I always liked those lines by the American poet, Walt Whitman. I have several times repeated them. They apply to-day most aptly. He said: “Now understand me well — it is provided in the essence of things that from any fruition of success, no matter what, shall come forth something to make a greater struggle necessary.” The problems of victory are more agreeable than those of defeat, but they are no less difficult. … We shall need to use the stimulus of victory to increase our exertions, to perfect our systems, and to refine our processes.

This is an eloquent restatement of “chazak chazak v’nitchazek.” Unlike the tagline of the beer ads, once a job is done, it is not “Miller Time.” Victory brings with it a multitude of problems, and the greatest of them all is being spoiled by success.

Every new chapter requires an even greater struggle.

• • •

The catastrophe of Oct. 7 occurred due to the sin of overconfidence. Multiple warnings were ignored, while the political and military leadership clung to the assumption that the enemy simply would not attack despite clear evidence to the contrary. No one remembered the lesson of “chazak chazak v’nitchazek.”

In retrospect, this war will probably be seen as a defeat and victory mashed up together, much like the Yom Kippur War 50 years ago. What happens the “day after” has been discussed almost from the very beginning. Pundits, politicians and polemicists all offer their visions. They are planning for a very different political and social landscape.

While a new blueprint is probably necessary, even more important than that is a new mindset.

History is considered by Judaism to be a form of revelation. In a recent seminar, I made mention of Emil Fackenheim’s “614th commandment.” Fackenheim was a prolific writer on the theology of the Holocaust, and believed that history is a form of revelation. The Holocaust, he argued, despite its horrors, carries the commanding voice of history. To Fackenheim, this voice declared: “Thou shalt not hand Hitler posthumous victories.”

That is a new commandment, the 614th commandment. One of his students paraphrased Fackenhiem’s four-fold view of this commandment as meaning: “Jews must remain Jews, they must remember the Shoah victims, they must not despair of man, and they must not despair of G-d.”

History as revelation is the very lesson of Purim. The Book of Esther meticulously excludes mention of God’s name. Instead, it urges us to hear G-d through the commanding voice of history.

Much like Fackenheim’s understanding, the practical commandments in the Book of Esther offer a series of lessons as well, which I would summarize this way: Evil exists. Celebrate salvation, and celebrate with friends. Care for the vulnerable. Connect to your community. Read aloud these lessons every year so you don’t forget them.

Actually, the lessons of history cannot offer a simple blueprint for the future; circumstances change all the time. Instead, they are meant to transform our perspective.

• • •

After Oct. 7, a commanding voice calls out to us again, asking us to see the world differently. Bret Stephens, in a brilliant column, writes:

“There used to be a sign somewhere in the CIA’s headquarters that read, ‘Every day is Sept. 12.’ It was placed there to remind the agency’s staffers that what they felt right after the attacks of Sept. 11, 2001 — the sense of outrage and purpose, of favoring initiative over caution, of taking nothing for granted — had to be the mind-set with which they arrived to work every day.

“There ought to be a similar sign in every Jewish organization, synagogue and day school, and on the desks of anyone — Jewish or not — for whom the security and well-being of the Jews is a sacred calling: ‘Every day is Oct. 8’.”

This is a powerful point. Jews must nevermore be naive. Our destiny can no longer depend on here today, gone tomorrow “allies,” and our security must depend on something more than a high-tech fence.

But the voice of history has much more to say about Oct. 7. One day a “Book of Oct. 7” will be composed, with all the stories of unity, heroism and optimism. And through these stories, we will hear God’s commanding voice, and learn lessons about the mindset we need in order to move forward into the future.

Allow me to share one such story. This past week I met a young woman from Kfar Aza, Or Tzuk, who spoke at an AIPAC conference.

On Oct. 7, Hamas terrorists murdered her parents. Her 25-year-old brother was able to survive by hiding under a bed; he stayed there for seven hours just inches from his mother’s body, soaked in her blood. (Or and her husband had gone away on vacation.)

Or told us how she promised her brother that whatever happens in the future, she will always care for him; he can come any day and move right into her house. And she told everyone that she was three months pregnant and had thrown up just before she got on stage.

When I spoke to her afterward, I asked Or why she decided to get pregnant just two months after her parents were brutally murdered. Her response was simple: Jews know they must choose life. Jews must always be optimistic, even in the worst of times.

Or said she drew inspiration from the Jewish holidays. Unlike many other cultures and religions, Jewish holidays are not unvarnished stories of joy; rather, they tell stories about how resilient heroes like Esther, Moses and the Maccabees overcame extreme challenges.

When speaking to Or, I realized that I was talking to a modern-day Esther. She has heard a voice calling out, telling her to choose life, to choose family, to choose community.

And that voice speaks to us too. This is the only way forward for the day after.