In this week's parsha, we learn about the ancestry of Moses and Aaron. "And Amram married Jochebed his aunt, and she bore him Aaron and Moses." Such a union is forbidden by the Torah (Levit. 18:12). Although this marriage took place before the Giving of the Torah, and was therefore not forbidden, there is something distasteful about it.
There is a midrash which asks: "Why did G-d choose a man who has a blemish on his ancestry to lead and teach the Jewish people?" The Chizkuni quotes another midrash, due to King David, which asks the same question about his own ancestry, which was blemished by the marriage of Boaz to a Moabite woman (Ruth). (The point is that marriages to Moabites are forbidden in the Torah. However this is interpreted as marriages between Jewish women and Moabite women. But again, this comes close to a forbidden practice.) And we could ask the same questions about further blemishes in the Royal line through David and Solomon: the relationships between Judah and Tamar, and between David and Bathsheba.
The second midrash quoted above gives the following answer to this problem: the purpose of this blemished ancestry is to make the person concerned maintain his humility, and not rise haughtily above his subjects (in the case of David) or his flock (in the case of Moses).
The following problem arises with this answer: if a man as great as Moses, who performed such feats as leading the Jews out of Egypt, leading them through the desert, and giving them the Law (each one of these no small accomplishment!) were inclined to pride or arrogance over these achievements, he would hardly be kept humble by such a little thing (by comparison) as a blemish of this kind; and similarly for David.
Think of a multi-millionaire, who, when he started out making money thirty years ago, was involved in some shady deals, but is now a big philanthropist and a respected member of the community. He isn't going to continue beating his breast about his dubious operations of long ago. He'll be proud of his achievements since then, and his present status.
The answer to this problem, I think, is this. Most of us, like our multi-millionaire, look back with pride to our positive achievements over the years, and tend to forget our less praiseworthy actions. But with a tzaddik it is the opposite. He will ignore his many great accomplishments, and be painfully aware instead of the few times he fell short of his own high standards.
There is a story of a man who went to a Chassidic Rabbi with the question: "Rebbe, I can't understand why G-d sends me so many troubles. I do so many mitzvos! I go to minyan four times a week," he said, ticking off on his fingers, "learn Torah twice a week ..." "Your problem," the Rebbe interrupted him, "is precisely that you can list all your mitzvos!" A real tzaddik cannot recall his many mitzvos from one day to the next -- he does not dwell on them, but on his imperfections.
The most honored title that a Torah scholar can gain is not "Rav" or "Rebbe" but "Talmid Chochom", a student of wisdom. Such a person realizes that he can, and should, always be learning from others. "From all my teachers I gained wisdom" (Psalm 119:99).
In Pirkei Avos (4:1) we read: "Who is rich? He who is content with his lot." This refers only to one's material possessions! The mistake that many people make is to be content with their spiritual possessions. We should never be satisfied with our spiritual attainments, but strive to improve them