This week’s Torah portion begins: “And Jacob went out”. Where was he going? He was left to wander, traveling outside of Israel. In this story of the Torah, Jacob’s departure outside the Land represents the entire people of Israel in the form of one person alone. Essentially, he provides us with the paradigm of what the exile signifies for the people of Israel.
What is Jacob’s (Israel’s) going to do there? He aims to prove his moral superiority. Jacob finds himself in a seemingly inferior moral position when he enters the land. Esau, his older brother, believes that he stole his birthright. “I am the firstborn, and Jacob took the blessing rightfully belonging to me." When Jacob arrives at Laban's house, Laban deceives him by switching the older sister in place of the younger. Upon realizing he had been cheated, Jacob asks Laban, "Why did you deceive me?" In response, Laban replies, "It is not done so in our place to give the younger before the firstborn, unlike what you did when you make yourself the firstborn. Here, Laban emphasizes, the firstborn takes precedence over the younger." After hearing Laban's claim, Jacob cannot respond. He knows he has no chance of convincing Laban of his moral superiority.
In contrast, when four firstborns are born to Jacob—Reuben (from Leah), Dan (from Bilhah), Gad (from Zilpah), and Joseph (son of Rachel)— the process of correction begins. When Reuben is born, he is named Reuben, meaning ‘behold, a son.’ The great medieval commentator Rashi, explained the name: "Behold the difference between the son of Laban and the son of my father-in-law." She was referring to Esau’s behavior in contrast to Reuben’s regarding a younger brother taking the right of the firstborn. Esau continues the tradition of Cain and Abel when Cain, the older Cain, murders Abel, his younger brother. In contrast, Reuben, inspired by the Holy Spirit, not only does not resent that Joseph is made the firstborn but later stands up for him, trying to save Joseph from the pit thrown where the other brothers cast him. In Reuben’s behavior, the process of correcting the negative reputation commenced.
With Dan’s birth, it's even more so. Dan is born so that Joseph can be born. This is why Rachel, a woman with no sons at all, gives her maidservant Bilhah to Jacob, for when Gad is born, it is so that she, who already has sons, will have more sons.
When Joseph was born, Rachel said, "God has removed my reproach." She called his name Joseph, saying, "May the Lord give me another son."
This is the first time in history that a firstborn son is born from the same father and mother so that the younger brother can be born.
All this is evidence of Jacob's absolute superiority over Esau. Therefore, when Rachel gives birth to Joseph, Jacob tells Laban, "Send me on my way so that I may go to my place and to my country."
Why was the birth of Joseph the trigger for his departure? Rashi explains once again. He wrote in his commentary that Jacob was prepared to return to confront his brother Esau now that a more deserving younger brother could replace the biological firstborn. This is Isaac's right over Ishmael and Jacob's over Esau's.