"Every man shall encamp by his own standard, with the sign of their fathers house." (Num. 2:2)

Each standard was to have a colored cloth hanging in it, the color of one being unlike the color of another. The color of each standard corresponded to that of the stone fixed in the breastplate [of the High Priest, on which the name of that scribe was engraved], and by this method everyone would recognize his standard. (Rashi)

On Reuben's standard there was a figure of a man decorated with mandrakes….

But Rabbi Abraham ibn Ezra commented: "There were signs on each of the [four main] standards. Thus the ancients sages said that on Reuben's standard there was a figure of a man decorated with mandrakes, and on Judah's standard there was the form of a lion, to which Jacob had compared him, and on Ephraim's standard was the figure of an ox, based upon [the expression that Moses used in speaking of that tribe], "the firstborn of his ox", and on Dan's standard was the figure of an eagle. Thus [the four signs on the four main standards] were similar to the four figures that the prophet Ezekiel saw [in the Divine Charriot]."

The Tent of Meeting was in the exact center, with the camps of the Levites surrounding it in the midst of the camps [of the other tribes], as is mentioned in Sefer Yetzira: "And the Holy Temple is placed exactly in the middle."

I have furthermore seen in the Midrash [the following text]: "And just as the Holy One, blessed be He, created four directions in the universe, so He surrounded His Throne with four "living creatures", and high above them all is the Throne of Glory. The Holy One, blessed be He, told Moses to arrange the standards in a manner corresponding to these directions.

There [in Bamidbar Rabba] the Rabbis also interpret [the division of the tribes of Israel according to four standards as] corresponding to the four groups of angels [surrounding the celestial Throne]. The Midrash also explains there that [the division of the tribes was not arbitrary but] it was all in wisdom, [showing] honor and greatness to Israel, and that therefore Scripture mentions everything in detail.

[Adapted from Rabbi Dr. Charles Chavel's annotated translation.]