The Talmud (Chagiga 5b) tells us that G-d "sheds three tears" over the tragedies of the human situations that people bring upon themselves. One of those tears is over people appointed to positions of leadership who misuse their authority for the purpose of self-aggrandizement. It is a psychological principle that power corrupts. It is very unusual for one to wield a lot of power and to remain unaffected. The parsha speaks of the case of the Jewish king of Eretz Yisroel (the land of Israel) sinning and being able to offer a special kind of "korban chatas" ("sin offering"). The expression used is, "asher nasi yecheta" ("that a leader shall sin"), and the Rabbis pointed out that the connotation of the phrase is that "it is the good fortune and to the credit of that generation" that their chosen leader is able to admit his mistakes. "Hakaras hachet" (recognizing that one has sinned) is difficult for any intelligent person, and even more difficult for one in a position of leadership. If the chosen leader is able to admit his errors, this indicates that the people had chosen wisely.
When Rav Chaim Soloveitchik had to chose a dayan (rabbinical judge) for the city of Brisk to assist him in paskening the shailos (issuing Jewish legal rulings in response to questions), he preferred Rav Simcha Zelig Regeur over the other candidates because he alone was able to admit that he did not know how to pasken on several of the issues that Rav Chaim had posed to him. The Talmud recommends even for laymen that we all "train ourselves to say that we do not know". This criterion is even more crucial for appointing one to a position of leadership.
The Talmud tells us that in the overwhelming majority of cases the views of Beis Hillel have been accepted as opposed to those of Beis Shammai. One of the reasons given for this is that generally speaking the students of Beis Hillel were more humble than those of Beis Shammai. In general, the students of Beis Shammai were more brilliant than those of Beis Hillel, and often found it too difficult to humble themselves to the degree of their counterparts. The assumption is that the more humble the individual is, the better the chance he has to discover the deep truths of the Torah.
Moshe Rabbeinu was the greatest Torah scholar of all times, precisely because of his great humility. The opening mishna in Avos states that "Moshe kibel Torah meSinai" The simple translation of the phrase means that he received the Torah at the location of Mt. Sinai. There is a famous interpretation offered by both Chassidic and Misnagdishe rabbonim, that Moshe was worthy of receiving the Torah because he was like Mt. Sinai, i.e., because of his humility. Just as Sinai was not so tall a mountain, and acted with humility in context to the other mountains, and was therefore chosen by G-d for the purpose of matan Torah in lieu of other tall mountains, so too, Moshe Rabbinu, Beis Hillel, and anyone else humble of spirit, stands a better chance of succeeding in clarifying the truth of the Torah.
When choosing a rabbi of whom we ask sheilos, or when selecting one for a position of leadership, the criterion of humility should be high on the list of qualities to look for. It is indeed the "good fortune of the generation" to be able to chose as their leader someone who is in the habit of saying "eini yodeah", and humble enough to admit on occasion that he erred.
At the end of the first word in Chumash Vayikra there is a small aleph, as opposed to the first letter of the word "Adam" at the beginning of Sefer Divrei Hayamim, where there is a large aleph. The small aleph is understood as representing the humility of Moshe Rabbeinu. The Baal HaTanya explained, along the same lines, that the extra-large aleph of "Adam" represents the arrogance of Adam Harishon. The chumash tells us that the cause of the original sin was the arrogant attitude of Adam and Chava who believed the words of the Snake, who said that if they ate from the Etz Hadaas they would become as great as G-d! Fortunate is the generation who understands enough to appoint as its leader the person with the small "aleph" like Moshe Rabbeinu.