Kabbalah su Genesi 25:31

"And Jacob cooked pottage." In the name of Rabbi Acha, Rabbi Ba said that the nature of the world never changes. Come and behold, it is written, "And Jacob cooked pottage (Heb. נָזִיד)," as in the verse "they dealt (Heb. זָדוּ)" (Shemot 18:11), which was translated into Aramaic as "they thought." It means that the heart thinks of and contemplates Torah, which represents the knowledge of its Creator. Thus, it is written, "and Esau came from the field, and he was faint" (Beresheet 25:29). It is the nature of the liver to go out hunting and swallow with its mouth. If it does not find any prey, it becomes tired and says to the heart, 'Before you think of the words of Torah, think of eating and drinking to nourish your body.' This is the meaning of the verse, "and Esau said to Jacob 'Give me to swallow, I pray you, of that red pottage,'" for it is my way to swallow the blood and transmit it to the other parts; "for I am faint," without food and drink. And the heart replies, 'Give me the first and choicest of whatever you swallow, give me your birthright,' this is the meaning of "Sell me this day your birthright" (Ibid. 31). That is, swear by your desire. As the heart contemplates food, the liver swallows. If it were not for the heart, longing and thinking about food, the liver and other organs would not be able to swallow. As Rabbi Yosi said, This is the way of slaves, who do not to eat before their master.