Two midrashim propose opposing understandings of the fragrance that Yitzchok inhaled.
One midrash, cited by Rashi, observes that Yaakov was clad in a goatskin, whose scent is particularly noisome. The pleasant scent simply could not have come from Yaakov’s upper garment. The midrash proposes that a different scent completely masked and overpowered that of the goatskin. When Yaakov entered, a scent of Gan Eden entered with him. It was this scent that Yitzchok responded to with a
The gemara 2 takes a different approach. It notes the similarity of the words begadav/garments and bogedav/renegades. Yitzchok sensed through Divine inspiration the sweet savor of the mitzvos of even the renegades of Israel, the sinners who nonetheless are saturated with good deeds.
These approaches seem to be entirely unrelated. That is not necessarily true, however.
Pirkei d’Rav Eliezer 3fleshes out the conversation surrounding Yitzchok’s berachah to Yaakov. The scene begins with Yitzchok telling Esav that this evening, the night of Pesach, everyone would be reciting Hallel. Heavenly reservoirs of berachah would open up. It would be the perfect time to give him a berachah. He should prepare delicacies for him, so that he could give Esav that blessing.
Rivka then has a similar conversation with Yaakov, adding that on this special night his descendants would be freed from servitude. Yaakov procures two kids and prepares them. One of the two was for the Pesach offering; the other was for his meal, so that the Pesach would be eaten as it is supposed to be, in a state of satiety.
Yaakov complied with Yitzchok’s request, and prepared a kid in the manner that his descendents would prepare one when released from Egyptian bondage.
Another midrash 4 describes the scene when that moment of deliverance in Egypt finally arrived. Many Jews balked at Moshe’s instruction to circumcise themselves. Moshe went ahead and prepared his korban Pesach. Hashem instructed the winds from the four corners of the earth to blow through Gan Eden, carrying its scent and embedding it in Moshe’s Pesach. The aroma was overpowering. The Jews gathered around Moshe, asking to be included in his korban. He, of course, reminded them that they would not be able to partake of it without first submitting to bris milah. This time they complied. The blood of circumcision comingled with the blood of the Pesach. Hashem took each person who participated, kissed him and blessed him.
We can assume that when Yaakov prepared the goat for his father as a korban Pesach, his intention was holy and pure, and succeeded as well to bring with it the scent of Gan Eden, as described in the first midrash we mentioned above.
Now the reason that G-d ordered the winds at the time of the Exodus to carry the scent of Gan Eden was to persuade those who initially refused His directive to perform bris milah. Yaakov understood, this, and thus beheld the great love that Hashem has for Jewish sinners! He comprehended how much good, how many mitzvos would come from those sinners – all the more so from the righteous of Israel.
Yaakov comprehended as well how Hashem would react – lifting each sinner, kissing them and blessing them. Yaakov therefore acted in the same manner. Sensing the scent of Gan Eden, he embraced the son in front of him, and gave him a berachah!
The two midrashim are but two sides of a coin. It is only together that we understand what Yitzchok felt as he was overcome with the urge to bless his son.
Sources:
1. Based on Be’er Yosef, Bereishis 27:27
2. Sanhedrin 37A
3. Pirkei d’Rav Eliezer 32
4. Shemos Rabbah 19:5