This is what Rabbi Yehoshua of Sikhnin says in the name of Rabbi Levi: Why are the names of the tribes not identical everywhere, but rather, at times this one precedes that one, and at times, that one precedes this one? It is so they would not say: The children of the wives are first and the children of the maidservants last, to teach you that these were not greater than those. Alternatively, why do these precede those? It is because they are the ceiling of the world. One who installs a ceiling properly places the thickness of this ceiling beam alongside one that is not its equal; therefore, this one precedes that one. From where is it derived that they are the ceiling [tikra] of the world? It is as Isaiah says: “Heed Me, Jacob and Israel, whom I called [mekora’i]” (Isaiah 48:12).