Genesis 25:
29. And Jacob cooked pottage; and Esau came from the field, and he was famished. 30. And Esau said to Jacob, Feed me, I beg you, with that very red [adom] pottage; for I am famished; therefore was his name called Edom. 31. And Jacob said, Sell me this day your birthright. 32. And Esau said, Behold, I am at the point of death; and what profit shall this birthright do to me? 33. And Jacob said, Swear to me this day; and he swore to him; and he sold his birthright to Jacob. 34. Then Jacob gave Esau bread and pottage of lentils; and he did eat and drink, and rose up, and went his way; thus Esau despised his birthright.
What stands at the heart of this scene is a moment where a man feeds his famished brother. This is an act of giving; and Esau clearly trusts Jacob, as one does not eat food from the hand of someone one does not trust. Jacob does not withhold the pottage and say, "This is mine. You can die for all I care." They are connected, and, as twins, their destinies are intertwined.
The Hasidic masters suggest a symbolism for Jacob and Esau as the "godly soul" and the "animal soul" inside us. One approach to the animal soul - bodily needs - is to try to stamp it out altogether through fasts and other ascetic actions. But I have discovered that when I try to ignore or deprive the lower soul, it doesn't work out well.[1] The body has its own reactions to being ignored, and will manifest an illness or other symptoms until it is heard.
So the path to spiritual growth is rather one that has to take our "lower" needs into account, to listen to them and engage with them in their own language so that they are "happy" and "satisfied."
In the Torah narrative, Esau, the lower soul, is starving and at death's door. In a case like this, it is up to Jacob, the higher soul, to stop and feed him, for his nourishment lies in Jacob's hands. They are brothers, twins. Jacob cannot simply withhold the pottage. Thus, the higher soul cannot withhold from the body its rest, quiet time, food, social life, and the other things it needs.
However, Jacob also does not have to act and react only on Esau's terms. If Jacob knows that the birthright will be much better used by him, as a more evolved being, he can offer Esau what he needs (food) in exchange for what will nourish him himself (birthright blessings). That is both fair and wise, and good for both ultimately, because it is not good for the lower soul to receive too many material blessings, as it will only make it coarser and more material.
Thus, Jacob speaks in Esau's language to offer him what he needs, but does not give in to life on Esau's terms, rather doing what he needs to do to work on his own, more elevated plane. The higher soul must not simply surrender to the lower soul's demands; it must use its wisdom to offer an exchange, such that while the self is getting its immediate needs fed, the soul is free to pursue its higher agenda. Balancing these two souls is the key to healthy spiritual and physical functioning.
[1] Rabbi Aryeh Nivin's coaching approach similarly holds that the "lower soul" cannot simply be ignored, and must be worked with skillfully.