As the book of Bamidbar opens, the Children of Israel are commanded to conduct a census:
And Hashem spoke to Moshe in the wilderness of Sinai, in the Tent of Meeting, on the first of the second month, in the second year of their exodus from the land of Egypt, saying: “Take a census of all the congregation of the Children of Israel by their families, by their fathers’ houses, according to the number of their names, every male, by their head count. From the age of twenty years and upward, all those that go out in the army in Israel, shall you and Aharon count them by their armies (L’TZIVOTAM)” (Bamidbar 1:1-3).

This is not the first time a census has been mentioned. When Hashem taught the detailed instructions for the Mishkan, the materials included a mandatory half-shekel coin which could be used to determine the number of the congregation:
And Hashem spoke to Moshe, saying: “When you take a census of the Children of Israel by their numberings, each man shall give a ransom for his soul to Hashem in numbering them, so that there not be a plague among them in numbering them” (Shemot 30:11-12).
 
According to Chizkuni (R. Chizkiya ben Manoach, mid 13th Century), the census in the beginning of Bamidbar is the first time the commandment in Shemot was fulfilled. Rashi, on the other hand, holds that the first census was taken at the time of the building of the Mishkan. The count “on the first of the second month, in the second year of their exodus from the land of Egypt” is the second time a census was taken.

What is the purpose of this census?

In verses 5-15, Hashem tells Moshe to obtain the assistance of the tribal heads (nesiim) for the census, and they are listed in proper order. As Ibn Ezra points out, first come the sons of Leah, Yaakov’s first wife, then the sons of Rachel, placing Ephraim before Menashe in accordance with Yaakov’s blessing (Bereishit 48:20), and then the sons of Bilhah and Zilpah, starting with the oldest Dan. (Levi is always treated separately.)

In verses 20-43, however, where the tallies of all the tribes are given, the tribes are listed in the order of their encampment, as will be explained in chapter 2. This change necessitates placing Gad after Reuven and Shimon. In other words, the census as reported anticipates the encampment, even before Hashem commands it.

When the camp is arranged, with three tribes on each side, flags play a central role:
And Hashem spoke to Moshe and to Aharon, saying, “Everyone by his flag (DIGLO), with signs (B’OTOT) according to the house of their fathers shall the Children of Israel encamp. At a distance, around the Tent of Meeting shall they encamp” (Bamidbar 2:1-2).

R. Yaakov Kamenetsky (1896-1981, “Emet L’Yaakov”) points out that the purpose of these flags and the structure of the camp cannot be to impart independence or a military configuration to the Children of Israel. They possessed these from the moment of the Exodus:
• And it was on that selfsame day that Hashem took the Children of Israel out of the land of Egypt by their armies (AL TZIVOTAM) (Shemot 12:51).
• …and armed did the Children of Israel ascend from the land of Egypt (ibid.,13:18).
Furthermore (if we may be permitted to add to R. Kamenetsky’s question), this configuration is part of the people’s legacy. As Rashi says, the twelve sons of Yaakov were so positioned when they carried his body to Canaan:
“With signs (B’OTOT) according to the house of their fathers — by the sign that their father Yaakov transmitted to them when they bore him from Egypt, as it is said, “And his sons did so for him, as he charged them” (Bereishit 50:12). Yehudah, Yissachar, and Zevulun were to bear him from the east, and Reuven, Shimon, and Gad from the south, etc.” (Bamidbar 2:2).
The encampment remained in the nation’s collective memory, ready to be actualized immediately upon their liberation. As R. Kamenetsky declares:
“Behold, they did not leave like slaves who flee from their masters, but as a free nation. So why did they wait a full year to organize the flags? I wonder!”

However, he says, each flag (DEGEL) and sign (OT) connotes a quality distinct to each tribe (see Ibn Ezra). In addition, each tribe is an army (TZAVA) unto itself. The existence of twelve different tribes, with their respective tribal symbols, could lead to disharmony (peirud levavot, “division of hearts”) within the people.

Once the Mishkan was erected and dedicated, however, the twelve tribes were unified by it. Only with the Mishkan at the geometrical and ideological center could the dozen disparate tribes become a united entity. Only with the Mishkan as a central purpose can the tribes’ dissimilar characteristics cooperate.

This idea is developed by the Maharal (R. Yehudah Loew ben Betzalel, c. 1525-1609; Baer Hagolah 6:8; Gevurot Hashem 13; Chiddushei Aggadot Yevamot 16b, Sanhedrin 21a; see also Sefer HaYetzira 5:2.). The number twelve signifies the limits of the three-dimensional world, like the twelve edges of a cube. Each of these has a distinct function and connection to Hashem. Even among the nations, there are twelve divisions (see Devarim 32:8): Avraham’s brother Nachor had 12 children (Bereshit 22:20-24), as did Canaan (10:15-19) and Yishmael (17:20, 25:16). However, they lack a unifying force.

The tribes of Israel are like the branches of a tree, subdividing from their common root. To combine their varied strengths, they must remain focused on Yaakov and the Torah. Thus the tribes encamp around the Mishkan, just as the twelve brothers encircled Yaakov when they took his body back home.

Like the instruments in an orchestra, diversity within the Jewish People can produce either cacophony or symphony. As Shavuot, the Season of the Giving of Our Torah approaches, we need to remember the Torah’s harmonizing power. When the Torah is our common mission, our music can fill the universe.