I am watching the footage from Sarah Techiya Litman and Ariel Biegel’s wedding in Jerusalem, and “unity” becomes more than a concept.

It’s real. It’s tangible. It’s right here in the room.

And it’s an act of defiance.

On November 13th, terrorists shot and killed Techiya’s father, Rabbi Yaakov Litman, and her 18-year-old brother, Netanel. “The whole floor (of the car) was full of blood,” said Techiya’s brother Dvir, when he tried to describe the horror to reporters.

But the Litmans didn’t let terror overcome them.

“Do not rejoice over me, my enemy,” wrote Techiya and her fiance Ariel on their wedding invitation. “For I have fallen but I have gotten up.” Then, they posted the invitation online, and publicly invited all of Am Israel to join them on their happy day.

And Am Israel did.

For one night, thousands of Jews from around the world set aside their political arguments and religious differences. For one night, they held hands and danced together, as brothers and sisters, united in their celebration of life.

Our enemies can fill our cars with blood and horror. But we can fill a wedding hall. We can rejoice together in the creation of a new family, and prove that despite our fundamentally different agendas and visions, we are still one family at heart.

* * *

But even as I am watching the footage, I can’t help but feel wistful and sad. Because, side by side with descriptions of the wedding, I find online arguments and nasty comments and debates.

Unity is wonderful, but can it truly last? What happens on the day after the wedding?

* * *

Sometimes I think that “unity,” as a concept, is simply too good to be true.

At times, it demonstrates wishful thinking. “Look at this display of national unity,” I enthused at a prayer for the three kidnapped boys last summer. But even as I basked in the glow of “achdut” (unity), other people expressed their apathy and disdain. “They are settlers,” they said. “What did they expect, living there? Why should we all worry about them?” And, perhaps worst of all, “well, now they have one son less. They still have plenty!”

At other times, the word “unity” is a form of manipulation, a hook on the fishing rod of conformity. “You can’t criticize your own people at times like this,” people told me after I denounced Jewish perpetrators of terror. “You are fracturing our achdut in our time of need.” But if unity requires the sort of blindness that immorality thrives on, perhaps we are better off without it in the first place.

And at times, unity truly happens…Only to be snatched away the very next day.

Take, for example, Jacob and Esau. Their reunion featured prominently in yesterday’s weekly Torah portion. We read about Jacob’s fears before their meeting. We read about his prayers, his conciliatory gifts, and his battle plans. And then we saw how the worst case scenario didn’t come to pass: “Jacob looked up and there was Esau…Esau ran to meet Jacob and embraced him; he threw his arms around his neck and kissed him. And they wept.”

Every year, when we read this verse, I weep too.

So many things stood between Esau and Jacob in this moment: Their own personal history of competition and deceit, their parents’ preferences and machinations, their fundamentally different outlooks on life. And yet, for this one moment in time, Esau and Jacob were merely brothers. For one moment in time, they set aside everything that divided them, fell on each others’ necks, and wept.

But this moment of unity was painfully transitory. In the very next moment, the reality of separation reasserted itself. Esau and Jacob didn’t sing Kumbaya together; They didn’t spend the evening talking everything through. Esau offered some sort of prolonged companionship for their families, and Jacob, ever wary, declined.

And he was right to decline. Just as he was right to fear the worst in the first place. After all, Esau was the impulsive, mercurial man who sold his birthright for a “red, red thing.” Such a man can’t be trusted not to change his mind.

But perhaps even more importantly, Jacob refused because his separation from Esau was more than a temporary estrangement, more than a misunderstanding to correct. The two twins represent fundamentally different ways of life. They could no more live together than we can ignore the political and religious disagreements within us.

And so the brothers went their separate ways. And so the guests in Techiya and Ariel’s wedding went their separate ways.

And the question remains: Do such moments of unity mean anything in the long run? Do they mean anything real the next day?

* * *

On Friday, I read people’s posts about Thanksgiving family squabbles, and I realized that I was asking the wrong questions all along. Or rather, I was asking the right questions, but I didn’t truly understand what they meant.

I asked, “Do moments of unity mean anything in the long run.” I didn’t ask, “Can they last.” I didn’t ask, “Can we always be actively united in a positive way.” If I had asked these other questions, the answer would have been no.

But meaning and permanence are not the same thing. We don’t need to remain actively united for the moments of unity to mean something to us. If anything, they mean more when we are at each others’ throats, arguing about the settlements or women rabbis or the gas deal. It is when we are separated, divided, and angry that we need our past moments of unity the most: We need them to remind us why we disagree so fiercely in the first place.

We argue because we are close. We argue because we share a past, a present, and a future. We argue because we share a national path, and the desire to make it the best possible path. We simply don’t agree about what “best” means.

And we argue so fiercely, because when families fight, the stakes are high, and disagreements hurt. Like some of my friends in their eventful Thanksgiving reunions, we attack each other because we care: about each other, about our joint national venture. And with the caring, comes the pain.

* * *

When I next read an opinion that upsets me, when I next encounter vitriol and anger from my fellow Jews, I will take a deep breath and pause. “This,” I will remind myself, “is not a negation of our unity. It is another expression of everything that brought thousands of Jews to Jerusalem last Thursday: The shared path that makes us a family at heart.”

Because even the day after the wedding, no — especially the day after the wedding — our unity is real, and means a lot.