The Gemara in Pesachim (Daf 6) establishes the famous principle of "Ein Mukdam U'me'uchar Ba'Torah," literally, "There is no 'earlier' or 'later' in the Torah." This means that Biblical narrative does not necessarily follow chronological sequence. For example, the Book of BaMidbar begins by recording G-d's command to Moshe in the second month, the month of Iyyar, and yet two Parshiyot later, in Parashat BeHaalotecha, we read of an event that occurred a month earlier, in Nissan. Thus, the arrangement in which the Torah narrates events does not necessarily reflect the sequence in which those events actually transpired.
Why is this so? Why doesn't the Biblical narrative present events according to chronological sequence?
The Rosh (Rabbi Asher Ben Yechiel, Germany-Spain, 1250-1327), in an interesting responsum, brings down one idea worth mentioning. He suggests that the Torah deviated from chronological sequence in the interest of maintaining peaceful relations among Jews in the synagogue. A person who is called to the Torah for an Aliya might complain that he was not called for an earlier Aliya, claiming that he is of greater stature than the one called before him. The Torah therefore presented events out of chronological sequence, so that such a person will realize that the events contained in his Aliya may very well have occurred before the section read previously. In this way, the Torah helps avoid strife and discord in the synagogue.
This expression in the Gemara – "Ein Mukdam U'me'uchar Ba'Torah" – lends itself to an additional reading, as well. The Sages tells us that the Jewish people are given three crowns: the crown of Kehuna (priesthood), the crown of Malchut (kingship), and the crown of Torah. Whereas the crown of Kehuna was assigned exclusively to the offspring of Aharon, and the crown of Malchut is reserved for the Davidic dynasty, the crown of Torah is available and accessible to one and all. Regardless of one's familial background and lineage, he has the opportunity to study Torah and become a great scholar. This critical message is alluded to by the Gemara when it established that "Ein Mukdam U'me'uchar Ba'Torah." When it comes to Torah, there is no such thing as "Mukdam" or "Me'uchar" – nobody is "ahead," and nobody is "behind." Everyone has an equal opportunity to study and master the Torah, and preference in this regard is not given to any individual Jew.