Sforno on Genesis 27:27/ספורנו על בראשית כ״ז:כ״ז

1וירח את ריח בגדיו, in order to expand his good mood by enjoying the fragrance. Our sages have described such an experience in Berachot 42 where they said: “which is something which the soul enjoys while the body does not benefit from it? It is a pleasant fragrance.”

2ויברכהו, What happened here is similar to what is described in Kings II 3,15, where the prophet Elisha, who had been unable to secure a prophetic vision he had craved, after listening and enjoying music played for him, was able to secure the prophetic insight for which he had been waiting. Yitzchok, who, though desirous of blessing his son Esau, had not felt in the right frame of mind to do so successfully, now was able to proceed with full confidence.

3ראה ריח בני, “you my son, take note that this is the appropriate fragrance.”

4כריח שדה, the field does not only provide physical nourishment, its herbs, etc., but in addition it provides enjoyment for the soul which appreciates and is nurtured by the body it inhabits inhaling the fragrance of these herbs. [Yitzchok establishes the connection between ריח and רוח, “fragrance” and “spirit,” something alluded to frequently when the Torah describes G’d’s reaction to man’s sacrifices, especially the incense. Ed.]

5 It is part of G’d’s goodness, 'אשר ברכו ה, to provide phenomena on earth which are apt to lift his spirits.