The original Tree of Knowledge bore fruit that combined good and bad, and since then they are always tied together in this world. But like oil and water, the truth cannot co-exist with iniquity; even when it is forcefully mixed, it separates eventually. The proximity to evil can, however, leave a certain impression even on the Tzaddik, like the foul odor of stagnant water that permeates into the oil above it. He must therefore always keep his distance from the wicked as much as possible, keeping the inedible part of the fruit, the peel, on the outside and the pure edible fruit on the inside; until the peel will eventually be thrown away and the eternal feast of pure knowledge will begin.
Although throughout Yaakov Avinu's life he had to deal with deceit, he never lost his internal integrity. Dodging Lavan's trickery, appeasing Esav's insatiable appetite with ludicrously abundant lip-service, he kept his distance from both of them and kept their evil intentions at bay. The Ariz"l teaches us the proper intentions of the Minchah prayer from Yaakov's presents to Esav: Like all our appointments and obligations that restrict us to the point of suffocation, Esav was out to strangle Yaakov. Only by breaking out of that whirlwind of vanities and attaching ourselves to the Almighty, can we release ourselves from their bondage, giving them only the superficial attention they require. The carefully numbered animals Yaakov sent, and the space (spelt like spirit - Ruach) he sent between them, destroyed Esav's fortified defenses totally.
Yaakov elevated himself through his tribulations till he was not deterred even when the angel of sin accosted him and tried to harm his essential goodness; the angel succeeded only in temporarily impairing his left leg (Hod). Only his encampment in the proximity of Shechem left a taint on his reputation: that brief delay in fulfilling his oath to return to Beth-El caused his daughter to be compromised, Shimeon and Levi to be repeatedly chastised, and eventually led to Yoseph being sold in that very place.
Although Yaakov's intentions were completely pure and noble, his timing, however, was ever so slightly out of sync; this was not the time to exercise patience. How much did we suffer through the course of history from that brief delay? How careful we have to be when in the wrong environment!
Going Further
The hebrew word for song, Shir, literally means a circle. A circle denotes completeness, for you cannot add to its length without breaking it, and it has no end. Moshe Rabbeinu summarized history in a song because history cannot be modified substantially, only details can be filled in, and it will ultimately reach its completion no matter what those details are.
Like a song, Moshe Rabbeinu's life could only be precisely 120 years. His life was a saga of completeness; any addition would have detracted from its perfection. He was also the one who transmitted to us the written Torah that, like a song, can only be written in a prescribed manner with specific letters. Not one letter may be added or subtracted. Thus is the nature of perfection - it must be all encompassing within the confines within which it is perfect.
There is perfection yet beyond perfection: limitlessness. Perfection is limited to a confined spectrum, whereas limitnessness is limitless. Yehoshua's leadership had a tremendous advantage over that of his teacher: it wasn't perfect. He, and all the leaders of the Jewish people after him who similarly transmitted the oral tradition, worked towards perfection. Slowly, they are bringing us closer and closer, yet until utter and complete perfection will eventually be reached there is no limit to how much you can do. Such is the nature of the oral law that Yehosha represented, it can be expanded and expanded until it encompasses all the endless meanings ensconced in the limited number of letters written on the holy Torah scrolls.
Hashem is called Ein Sof, endlessness, and the more energy we spend delving into His endless Torah, the closer we get to him.
Adapted from Rabbi Vali's book on Bereishis. Questions and subscriptions can be mailed to: the Yeshiva