How did the Levites erect the mishkan at each stop if they couldn't the first time?

Question

In Exodus 39:32–33, the Jews finished building the various parts of the Tabernacle and brought them to Moses. The commentary of Rashi:

They brought the Tabernacle, etc., because they couldn't put it up.… No one could raise it because of the weight of the boards [that formed the walls] that no one had the strength to put upright, and Moses raised it.

That's good and well for the first time the Tabernacle was raised. But it was dismantled and raised again every time the Jews stopped along their travels through the desert (Numbers 10:17, 21). Rashi there (verse 21) explains that it was the descendants of Gershon and Merari who put up the walls — certainly not Moses, then (Exodus 6:16–20). How did they put it up in all their travels if they were unable to the first time?

Answer 1

Rashi says that Hashem set this up in order to honor Moshe. Once he set it up then it became possible for the Leviim to continue setting it up and taking it down. My son said at his son's bris (Yom shlishi Parshas Pekudei) that because of the kedusha of the mishkan, not even Moshe could (physically) put up the walls. Hashem had Moshe act and He caused the walls to be erected.

Once that was done, and the Chanukas Habayis completed, the kedusha of the mishkan had been established. Also, Moshe Rabbeinu had established that the mishkan was now completely set up. The Leviim had received their tasking and were now in the position of "working for Hashem". At this point, Hashem allowed them to carry out their appointed tasks and to succeed in taking down and setting up the mishkan.

This means that the reason that the Leviim could not set it up originally was a decree from Hashem as was the neis of Moshe (appearing) to set it up by himself. Once Moshe had completed his task, Hashem decreed that the Leviim would be able to perform their assigned tasks.

This is another way of teaching the lesson that a person does his hishtadlus (effort) but it is actually Hashem who causes the effort to succeed or fail.

We can see a similar situation with the Aron, which "bore its carriers"

Rashi

Now they brought the Mishkan to Moses, etc.: Because they could not erect it. Since Moses had done no work in the Mishkan, the Holy One, blessed is He, left for him the task of erecting it [the Mishkan], since no human being could erect it [by himself] because of the heaviness of the planks; and no human was strong enough to put them up, but Moses [was able to] put it up. Moses said before the Holy One, blessed is He, “How is it possible for a human being to erect it [the Mishkan]?” He [God] replied, “You work with your hand.” He [Moses] appeared to be erecting it, and it arose by itself. This is [the meaning of] what it says: “the Mishkan was set up” (Exod. 40:17). It was set up by itself. [This is found in] the midrash of Rabbi Tanchuma. -[from Midrash Tanchuma 11]

UPDATE

Our rav, on Shabbas Parshas Pekudei, cited Rav Yaakov Galinsky who calculated the weight of the kerashim. It was almost 4 metric tonnes per board. This is based on 58 cm. per amah. .5 grams per cubic cc of wood (atzai shitim is considered a light wood). The plated gold is estimated at 8mm thick at 19.5 grams per cubic centimeter. Thus the boards had to be put up by a neis.

Each board was 10 X 1.5 X 1 Amah = 2,926,680 cubic centimeters

.5 grams per cubic centimeter = 1,463,340 grams = 1,463.340 kilos = 3,219.348 pounds

gold covering (on inside and outside) (9 x 58) (excluding the pegs) x (1.5 x 58) x .8 cm x 2 (two sets of covering) = 72,662.4 cubic centimeters

19.5 grams per cubic centimeter x 72,662.4 = 1,416,916.8 grams = 1,416.9168 kilos = 3,117.21696 pounds

Answer 2

Someone told me today that he had heard Rabbi Yissocher Frand on an audiotape quoting another rabbi who had asked the question above and had answered it by saying (citing the Zohar) that there is more hindrance from the sitra achara against a holier endeavor so that, when the mishkan was first erected, there was more hindrance than on later occasions, and the boards, actually light enough for people to put up normally, proved too heavy the first time.

Answer 3

Ikkur Sifsei Chachamim (#10 in the Artscrol chimash) says this was one of the questions Rashi was coming to address. To paraphrase his words "about this Rashi explains that after Moshe erected it once 'by itself'(meaning through a miracle), and from that day on it was also erected through a miracle."

He is apparently basing his words on the Mizrachi who phrases it somewhat differently, but also takes for granted that there was a miracle every time it was erected.