Parshas Toldos begins with the story of Yitzchak but quite soon transfers to the story of Yaakov. Yitzchak emerged in the previous two Parshas as a miracle son and in Toldos he becomes quickly a father, his story submerged within that of Yaakov, the father of the tribes of Israel.
There are any number of seemingly strange events in Parshas Toldos. Rivka at first is doubting that she was right to even want children when she experiences the turmoil inside her and goes to seek an answer from G-d. G-d tells her that there are actually two enemy nations fighting inside her. Not exactly the most reassuring of news.
Then Esau appears willing to trade his birthright for some lentil soup and yet weeps and mourns when the blessings of the birthright fall of Yaakov. Yitzchak who is supposed to be righteous, for some reason loves Esav and insists on blessing him originally.
To understand a lot of this we need to go back to the first case of sibling rivalry in the Torah, that of Kayin and Hevel. Like Esav, Kayin was the elder brother and a man who worked the soil, had a harsh temper and took what he wanted. Like Yaakov, Hevel was a shepherd who cared for his flock and dwelled in tents. Hevel was the seemingly civilized man and Kayin the brutal savage, yet it was Kayin who went on to build the cities and Hevel who perished at his hands. Yet the civilization that Kayin went on to build was just as bloody and horrid as he was and in the end G-d had no choice but to destroy it, because a civilization in which Kayin had a part, was not one that could persist on the earth.
In Parshas Toldos, Kayin in the form of Esav, the ruddy man, the elder brother, the violent one and yet the one who had the potential to build civilization. The Roman empire we are told descends from Edom, Esav's people. One can look at Rome and at the greatness of its descendants and see why Yitzchak would have decided that the elder brother was the one fit to lead and rule.
And indeed in Parshas Toldos, the ending appears to be a retelling of the story of Kayin and Hevel, except that Esav appears on track to receive the blessings of his father. And when he does not, when he is rejected, Esav like Kayin, takes his rejection the same way, by plotting murder. And in doing so Esav shows his unfitness to lead, for rather than reforming in the face of divine rejection, he does not repent, merely lashes out at those whom G-d chooses.
Yet what is Yitzchak's intention really and why does he love Esav, when G-d himself goes on to proclaim that Yaakov have I loved and Esav I have hated? The real question is why do men love evil? Seemingly perfect enough to be a sacrifice to G-d, Yitzchak allowed himself to be guiled and fooled by his older son. Only when it was clear that G-d had allowed his younger son to claim the blessings, did Yitzchak bow to the inevitable.
But in reality we know the answer to that ourselves, when we take a look at Yaakov and Esav, which is the more compelling figure? Esav is the dramatic and brooding one, the murderous and interesting figure. If producers had to choose whom to make a movie about, it would obviously be Esav. Like many villains, he is the compelling one, the anti-hero, the bad boy, the rampager and the conquerer. His father's blindness is not purely a visual one but also an affection for something that is bad.
Esav is described as a hunter, a man who prowls the field. So too Kayin is a man of the earth who toils on the earth. This is why Yaakov trades the birthright for lentils, a product grown from the earth. The holy exchanged for the cursed earth. By contrast Hevel and Yaakov are herders of animals. When the Jews descend to Egypt as herders, they are despised by the Egyptians who work the fields and worship animals. In the end they transform Jews into slaves to work their fields and build their cities for them, the city building that Kayin had first initiated.
When Yitzchak scents Yaakov, he proclaims him to carry the scent of a field blessed by G-d and only then does he bless him. Yitzchak wishes very much to bless Esav and to believe that he is a field blessed by G-d and only when he is certain of that, does he make the blessings. Yet working a field is hard work, it is work that Yaakov had avoided while living in the tents, when he is exiled he is force to bear the heavy burdens and though they embitter him, he proves more than equal to the task.
It is no true surprise that Yitzchak would have chosen Esav, the Heathcliff figure, the future builder of cities over Yaakov, the scholar and the dweller in tents. After all Yitzchak had to fight for everything he had as did Avraham before him. In the pursuit of easy answers though, Yitzchak very nearly chose an evil man. That is why G-d made the choice between Kayin and Hevel and intervened from the start to make the choice between Esav and Yaakov to inform Rivka of her true mission, to make the right choice for her husband.
Where Chava made the wrong choice for Adam, leading to their expulsion and the curse of the earth, leading to Kayin, the man of the earth -- Rivka redeemed her choice by making the right one where her husband was prepared to choose wrongly. Where G-d had spoken to Adam and given him a mission that Chava violated, this time G-d spoke to Rivka and gave her a mission that Yitzchak nearly violated. But this time Rivka prevented Kayin, the murderer and the city builder from winning... instead Esav had to be satisfied with a blessing that gave him the power of the sword and of the field, temporary physical victories that could not stand up against the permanent victories of the spiritual powers that Yaakov would wield.