Seeing (or is it counting?) double[1]
שאו את-ראש כל-עדת בני-ישראל למשפחתם לבית אבתם במספר שמות כל-זכר לגלגלתם: פקד את-בני לוי לבית אבתם למפחתם כל-זכר מבן-חדש ומעלה תפקדם
Count the heads of the entire assembly of the Children of Israel, by their families and their father’s houses, by the number of the names[2], all the males, by their heads. Count the Levites according to their father’s houses and by their families. Count all the males from one month of age[3]
Sefer Bamidbar’s English name of Numbers is aptly put[4], as there are many censuses that are described throughout the book. This parsha alone contains two censuses, one of the Jewish people at large (excluding the tribe of Levi), and one exclusively of the tribe of Levi. The two censuses have some differences. One of them is the main census of the people was of all the males above the age of twenty. This is not like the census of the tribe of Levi, which counted all males from the age of one month and up. Another difference is regarding the general census of the people, the Torah stresses that they be counted by their heads. This requirement is strangely absent from the census of the Levites. Regarding this latter difference, why did the Torah leave out the requirement of counting by their heads?