In many respects, the Torah's account of Isaac's family reads like a replay of Abraham's. Many years of childlessness are followed by the birth of two sons—the elder one wicked and the younger one righteous. Isaac favors the elder son, Esau, much as Abraham is sympathetic toward his elder son, Ishmael, while Rebecca, like Sarah, perseveres in her efforts to ensure that the younger, righteous son is recognized as the true heir of Abraham and the sole progenitor of the "great nation" which G‑d promised to establish from his seed.

There is, however, a significant difference between the two sets of brothers.

Ishmael and Isaac were born of two different mothers: Ishmael was the son of Hagar, a former Egyptian princess still attached to her pagan ways, while Isaac was the son of the righteous Sarah. Furthermore, Ishmael was born when Abraham was still Abram and still uncircumcised, and can be said to belong to his father's imperfect past (Abraham was born into a family of idolaters and is even described as having himself worshipped idols in his youth), while Isaac was conceived after Abraham had attained the perfection signified by his name change and circumcision.

On the other hand, Esau and Jacob were twins, born of the same righteous mother and raised in the same holy environment. Their father, Isaac, was "a burnt-offering without blemish" who was circumcised on the eighth day of his life and who never set foot outside of the Holy Land. Unlike his father, he had no idolatrous past and no "pre-Isaac" period in his life. So where did Esau's "evil genes" come from?

Even more puzzling is the fact that Esau's wickedness seems predestined from the womb. If Esau had turned bad later in life, we might attribute this to the fact that every man is given absolute freedom of choice to be righteous or wicked. But how are we to explain Esau's gravitation to evil even before he was born?

The Lubavitcher Rebbe explains that the fact that Esau was naturally inclined toward idolatry was not, in and of itself, a negative thing. It meant that his ordained mission in life was the conquest of evil rather than the cultivation of good.

Jacob and Esau are the prototypes for two types of souls, each with a distinct role to play in the fulfillment of the Divine purpose in creation. Maimonides calls these two spiritual types "the perfectly pious" and "the one who conquers his inclinations"; Rabbi Schneur Zalman refers to them as the "Tzaddik" and the "Beinoni." Humanity is divided into these two types, writes Rabbi Schneur Zalman in his Tanya, because "there are two kinds of gratification before G‑d. The first is generated by the good achieved by the perfectly righteous. But G‑d also delights in the conquest of evil which is still at its strongest and most powerful in the heart, through the efforts of the ordinary, unperfected individual."

Thus Rabbi Schneur Zalman explains the Talmud passage which cites Job as crying out to G‑d: "Master of the Universe! You have created righteous people, and You have created wicked people!" The actual righteousness or wickedness of a person is not predetermined by G‑d—in the words of Maimonides, free choice is "a fundamental principle and a pillar of the Torah and its commandments," without which "What place would the entire Torah have? And by what measure of justice would G‑d punish the wicked and reward the righteous?" Yet Job is right—G‑d does indeed create "righteous people" and "wicked people" in the sense that while certain souls enjoy a life wholly devoted to developing what is good and holy in G‑d's world, other souls must struggle against negative traits and ominous perversions implanted within them in order to elicit that special delight that can come only from the conquest of evil.

This, says the Lubavitcher Rebbe, is the deeper significance of Rashi's commentary on the opening words of our parshah. Citing the verse, "And these are the generations of Isaac," Rashi comments: "Jacob and Esau who are mentioned in the parshah." The simple meaning of this commentary is that the word toldot ("generations") can also refer to a person's deeds and achievements (cf. Rashi's commentary on Genesis 6:9); Rashi is telling us that here the word toldot is to be understood in its literal sense—the children of Isaac, though these are named only further on in the parshah.

On a deeper level, says the Rebbe, Rashi is addressing the question: How does an "Esau" come to be a descendant of Isaac and Rebecca? How do two perfectly righteous individuals produce an offspring who is evil from birth?

So Rashi tells us: the "generations of Isaac" are the "Jacob and Esau who are mentioned in the parshah." The wicked Esau we know is not a product of Isaac but the result of Esau's own failure to overpower his negative inclinations. The Esau of the parshah--Esau as viewed from the perspective of Torah, where everything is seen in its innermost and truest light—is not evil, but the instrument of conquest over evil. The Esau of the parshah is the purveyor of the "second delight" and an indispensable element of the purpose of life on earth.

In this also lies the deeper deeper meaning of the Midrash that describes Jacob and Esau fighting in the womb "over the inheritance of the two worlds" (i.e., the material world and the "world to come"). This would seem to be one area in which they would have no quarrel: the Esau we know desires the materialism of the physical world and shuns everything that is G‑dly and spiritual, while the reverse is true of Jacob. So what were they fighting over?

Explains the Rebbe: The "world to come" is not a reality that is disconnected from our present existence. Rather, it is the result of our present-day efforts in dealing with and perfecting the material world. The world of Moshiach is the culmination of all positive achievements of history, the era in which the cosmic yield of mankind’s every good deed will come to light.

In other words, our present world is the means and the "world to come" is the goal. This is the deeper significance of Jacob’s claim on the "world to come," and Esau’s (and here we speak of the “Torah’s Esau,” the righteous conqueror of his inclinations) preference for the present world. Jacob sees perfection as the only desirable state of man, while Esau sees the struggle with imperfection as desirable in and of itself.

Yet both Jacob and Esau recognize the necessity for both of “the two worlds,” for the process and its outcome. The “perfectly pious” man also requires the material world as the vehicle that leads to ultimate perfection. And the “conqueror” also sees perfection as the goal to which his efforts lead. For although his purpose in life is defined by the process itself, a process, by definition, must have a goal.

So this is their "fight." Jacob and Esau each lay claim to both worlds as part of their life’s endeavor. But their priorities are reversed. To the Jacobs of the world, the material world is but a tool, a means to an end. To its Esaus, man’s material involvements and the struggles they entail are what life is all about. A futuristic vision of perfection is necessary, but only as a reference-point that provides coherence and direction to the “real” business of life.

The tension between them over their differing visions of the “two worlds” is not a negative thing. It is the result of two world views, both positive and necessary, both indispensable components of man’s mission in life.