There are 248 “do this” mitzvahs in the Torah (and 365 “don’t do this” mitzvahs).

Counting in chronological order, number 247, the second-to-last mitzvah that Moses delivers to the Jewish people, is the mitzvah of Hakhel: Assemble the people once in seven years and relive the giving of the Torah. (Read about how that is done here.)

But why? What is it about this particular mitzvah that requires it be given on the last day of Moses’ life?

Is it because it’s a mitzvah you can only do in the Land of Israel?

There are plenty of agricultural mitzvahs that can only be performed in the Land of Israel. That didn’t stop Moses from instructing the people in them long before.

Well, you’ll say, this is different. It’s a commemoration of receiving the Torah at Mount Sinai. As long as they are in the wilderness of Sinai, hearing Torah from Moses, removed from the mundane activities of seeding, harvesting and protecting their land, they don’t need a commemoration. You don't sit down and look through your family vacation shots while you're still inside Disney World.

But now that Moses is handing things over to Joshua, who will take them soon into the promised land, now they need to be told, “Don’t allow yourselves to forget this experience. Replay it once every seven years!”

Sounds good. But not very Moses-like.

In the wilderness, they were surrounded by the “clouds of glory” that protected them from sun and sandstorm. Moses told them that once they enter the promised land, they should celebrate the Festival of Sukkot. They were to dwell in temporary huts as a commemoration of the divine protection they had received in the wilderness. He told them that long before they were ready to leave, while those clouds still hovered over their heads.

And what about Passover? Even before they had actually left Egypt, as they were assembled in Ramses, Moses stood there, telling them, “You’re about to leave for the promised land. When you get there, you’re going to have children. They will never have witnessed this great miracle. So you will have to make a Passover Seder every year to tell them the story, and eat matzah for seven days, too.”

So why doesn’t Moses stick to form and right there and then at Mount Sinai tell the people, “Remember this day! Relive it with your children! Make an assembly once every seven years!”

Why is Hakhel the only commemorative mitzvah that has to wait until the eleventh hour, just as the experience it is commemorating is coming to an end?

A simple answer: Only now has it been established that Moses is not coming with us.

As long as Moses is in the picture, the experience of receiving the Torah at the foot of Mount Sinai goes on and on. Even once farming the land, every year is guaranteed to be a Hakhel year.

But now it’s official that Joshuah is replacing Moses. Moses pleaded with G‑d for an entry pass, but he was turned down. If so, a once-in-seven-years replay suddenly becomes vital.

That also explains the very last mitzvah that Moses transmitted, number 248: Everyone must write a Torah scroll for themselves. (Today, that mitzvah is fulfilled anytime you buy a Torah book for your home.)

With Moses around, who needs a book? If you’re living by a water fountain, why buy bottled water?

Only without Moses on the scene do you need a hard copy, a tangible manifestation of the Torah he taught us.

So imagine now you’re one of those people who came of age in the Sinai Peninsula, camping out day and night with Moses and 600,000 other Jews, many of whom held a vivid memory of the sights and sounds of G‑d’s voice booming on the sixth of Sivan of that year they left Egypt.

Every once in a short while, the trumpets sound and everyone rushes to hear what Moses will teach next—teachings delivered to him from the same divine voice everyone heard at Mount Sinai. For months following, the entire camp is buzzing with discussion and debate over this new divine teaching.

Could you imagine making a commemoration of all this in the future?

No way. This was an experience that could never end! If it would end, how could such a nation possibly continue to exist? How could anyone continue forging this 248-connection/365-parameter bond with the Infinite without the total awareness of “G‑d is speaking to us right now” every day?

No, you would say, we’re holding on to this for eternity. Moses can’t leave us. Ever.

And now, G‑d informs you through Moses that He has other plans. You and the rest of the nation are going to have to go it on your own. Not entirely on your own—you'll have Moses’ prodigy, Joshua.

And Moses, too—as the rabbis said, “Moses never died. He just took over from a higher place.”1 Just like he led you then, he leads you now.

But visibly, with your very human eyes, it will be up to you to keep the inspiration alive.

So Moses says, “To do that, to hold onto a glimmer of this experience of Sinai, this is what you will need to do:”

“Once in seven years, relive Sinai. A representative of mine will stand there and read from this Torah I transcribed for you. And you, every one of you, men, women, children, the deaf and the blind, the learned and the illiterate, all as one, will hearken with awe, with trembling, so that love and fear will be planted in your hearts and grow with every mitzvah you do.”

Until we are all together once again in the final, eternal Temple in the promised land.

See Likutei Sichot, vol. 34, pg. 187.