This week's Parsha begins with a Posuk commanding Moshe Rabbeinu to have Bnai Yisrael bring "שמן זית זך כתית למאור להעלת נר תמיד," "pure olive oil to cause the light to burn continually" (שמות כ"ז:כ'). Rashi (שם בד"ה כתית) explains that only the first drop of oil which comes out of the pressed olives was acceptable for the Menorah, while any other oil produced by even crushed olives was permissible for use with the Korban Minchah, whose ingredients included oil. For the Menorah, furthermore, only the purest possible oil which contained absolutely no sediments or impurities at all, was necessary, as Rashi (שם) stresses.
Rav Moshe Feinstein, in his Sefer דרש משה, explains the symbolism of the pure olive oil. He writes that the Menorah represents the wisdom of Torah and, by extension, the teachers of Torah who are imbued with that wisdom and who guide the people in the ways of the Torah. Therefore, just as the oil for the Menorah must never have been clouded with impurities and sediment, so too must the teachers of Torah be pure and never open to suspicion. It is thus particularly important for Torah scholars and teachers to behave honestly and in a manner that is beyond question and suspicion. A similar idea is found in the Mishnah in Shekalim (פרק ג' משנה ב') which states that the garments worn by the treasurer of the Beis HaMikdash when he went to designate public funds in the Beis HaMikdash for the purchase of animals for Korbanos could not have any pockets. Moreover, even his pants could not have any cuffs. In this way, no one would have doubts about his honesty and perhaps accuse him of sneaking some of the funds for himself. Since the person was a role model, involved in holy work, his conduct has to be absolutely above reproach. He too had to be pure like the olive oil.
Chazal teach us about the way we should view our teachers and Torah leaders, saying that even if one sees a Talmid Chochom commit a sin during the day, he shouldn't think badly of him the next day because he certainly must have done Teshuvah for it during the night. Chazal are thus teaching us about how our teachers must be respected by their followers and students. But as mentioned, our teachers must demonstrate that they are deserving of this high level of respect by behaving properly themselves. Nobody is perfect, and even great people sometimes make mistakes. But if one's conduct is usually correct and one's behavior is usually pure, we must assume that when such a person sins, it was as a result of a temporary lapse which surely is immediately rectified.
We must all treat our teachers properly, and our teachers must learn this lesson from the pure oil of the Menorah. The Mishnah in Pirkei Avos (פרק א' משנה י"א) says "חכמים הזהרו בדבריכם," teaching that Talmidei Chachomim must be extremely careful with their words. Rav Moshe Feinstein adds that they certainly must also be careful with their actions, and only then will they be deserving of the respect of their followers. Only if both the leaders and their followers behave in the correct manner will we see the light of Torah shine constantly, as the Posuk (שם) implies by commanding that the flame must burn constantly.