The picture presented to us at the opening of parshat Vayeishev is one of almost idyllic perfection: Jacob's family is complete, his children are all loyal to his ideals, he has amassed great wealth, he has returned to the patriarchal seat in the Holy Land, and he has assumed the mantle of leadership. Moreover, he has solidly established his reputation by physically and spiritually overcoming three adversaries-Laban, Esau, and Shechem--and he is both esteemed and feared by the surrounding population. It would seem that all that now remains for him to do is to continue raising and guiding his family until it grows large and viable enough to constitute a people ready to receive the Torah. Even the name of the parsha, Vayeishev, which means "he dwelt," evokes an image of pastoral serenity.
After all the suffering he underwent, Jacob thanked G-d for this respite and asked Him to grant him continued tranquility. Clearly, he reasoned, he could fulfill his Divine mission better if unburdened by enemies and other worries. Thus, Jacob asked G-d for tranquility for the same reason that we long for the messianic future: in order to be free of all the impediments to fulfilling Gd's will in the fullest way possible. And indeed, G-d approved of Jacob's desire and granted his petition, at least to a certain extent: He allowed him to enjoy relative peace and comfort for a full nine years after arriving in Hebron.
But, as we immediately discover, there was a pernicious sibling rivalry brewing beneath the tranquil surface, which, when it emerged, would threaten to destroy the family and dash any hopes that this brotherhood would ever become the bearers of the patriarchs' vision. First, Joseph was sold into slavery by his brothers; then Judah parted company with them to form an alliance outside the family. Jacob himself remained inconsolable over the loss of Joseph. It would seem, then, that the rest of the parsha--that is, all but its first verse--reflects anything but the tranquility implied in its name.
To understand this seeming contradiction, let us recall that Jacob knew that fulfilling the Divine mission of making the world into G-d's home was dependent upon his overcoming the metaphysical power of Esau, and that Joseph embodied the spiritual qualities that would facilitate that achievement. Jacob therefore saw Joseph as his natural successor. Thus, although the last six parshiot of the Torah are devoted to Jacob, the last four of these six detail how Joseph fulfilled his father's expectations of him, providing the leadership needed by the next generation.
However, whereas Jacob chose to focus on Joseph's inner spiritual qualities, Joseph's brothers could not but notice that he was given to worrisome behavior, evincing arrogance and conceit that was alarmingly reminiscent of Esau's! The fact that their father openly treated him as their superior, apparently overlooking his shortcomings, only reinforced their association between him and Esau: after all, Esau's father Isaac was also deceived into thinking that his favored son was the rightful heir despite his outward behavior.
The brothers therefore concluded that just as there were children in the first two generations of Abraham's family who, for the good of the cause, had to be cut off, so, too, was it proving to be with the third generation. Rather than being the antidote to Esau, Joseph himself was the new Esau, and had to be eliminated.
Once Joseph's brothers were unequivocally convinced that he was unfit to rule, Divine Providence had to arrange for them to be convinced otherwise, and so began the protracted saga of Joseph's odyssey in Egypt.