In the Zohar, Rabbi Yehuda addresses the question of why Abraham and Isaac had to experience starvation and famine in their respective lifetimes: at the time G‑d wishes to shine into the soul of a person, He strikes the body to weaken it, in order that the soul should rule over it, for as long as the soul is equal in power in the body, the soul cannot be in control of it. When the body is broken, the soul rules over it.
According to the Zohar, the sin of the Tree of Knowledge of Good and Evil comprised the three cardinal sins that a Jew is commanded to lay down his life rather than transgress: idolatry, murder, and infidelity. The Arizal teaches us that Abraham rectified the sin of idolatry when he was thrown into the fiery furnace in Ur. Isaac was attempting to have Esau rectify the murder-aspect of Adam's sin by having him bring him a two-flavored dish acquired by killing. Rebecca sought to rectify Adam's sin of listening to his wife for improper purposes by having her son listen to her for proper purposes.
The scoffers of that generation maintained that Sarah had been impregnated by Abimelech and that Isaac was the issue. They claimed that, had Abraham been Isaac's father, it would have been impossible for Isaac to have fathered a son such as Esau who pursued married women to commit adultery with them under the noses of their husbands. Isaac's extraordinary wealth and material success, the fact that he was sanctified on Mount Moriah, and his life-long residence on the holy soil of the Land of Israel, all served to show that he was indeed a true son of Abraham.
And Isaac prayed fervently [in Hebrew, "vaya'etar"] to G‑d in the presence of his wife.
How is that the prayer of the righteous can reverse the conduct of G‑d from that of judgment to compassion? The answer: "measure for measure." Because the righteous convert any longing and desire into a desire for closeness to (i.e. love of) G‑d, so does G‑d convert his attribute of judgment into an attribute of mercy.
This doesn't apply only to the righteous. Every Jew has this potential. When one feels love for a certain person or even an animal, one should think, "Where is the source of all love, from where does love come?" Inevitably one will arrive at the answer: from G‑d.
When she passed by the house of study headed by Shem and Eber, Jacob tried to get out; when she passed by a temple of idolatry, Esau tried to get out, since Jacob was drawn to the direct path of ascending the ladder of divine consciousness by increasing (quantitatively and qualitatively) in knowledge and good deeds. Esau, in contrast, was drawn to the indirect path of championing goodness by combating evil.
A Jew's Hebrew name is an expression of the essence of his soul and the theme of his life's work. The fact that Jacob emerging from the womb holding on to his twin brother Esau's heel was noteworthy enough that his parents named him for this event meant that throughout his life, his service - and that of all of his descendants - is to draw down G‑dliness even into the lowest levels of this physical world.
This is the message of the name "Jacob" (in Hebrew, "Yaakov", made up of the letter yud and the word "ekev"): yud, the first letter of G‑d's name, the source of all holiness, and "ekev", "heel". Jacob's work is to draw the yud, G‑dliness, into the heel, even to the heel of Esau, the archetype of physicality.
The verses regarding Isaac's wells save a chasid's livelihood