remembering what's important

There are two Midrashim in VaYigash that I think everyone knows, but I don't think most people know that they go together hand in hand.  Everyone knows that Ya'akov sent Yehudah to set up a yeshiva in Goshen before he got there.  Everyone also knows that Yosef sent agalos, wagons, to Ya'akov to hint to him that he remembered that the last thing they learned together was the parsha of eglah arufah (eglah and agalah sound the same).    What I don't think people know is that this second Chazal is brought as a proof to the first.  After telling us that Ya'akov sent Yehudah to set up a yeshiva, the Midrash continues, "Teida lecha she'hu kein....," Know that this is so...," and the Midrash then tells us that Ya'akov was not convinced that  that Yosef was alive until he saw the agalos that were the reminder of eglah arufah.     

What does one thing have the do with the other?  How does the fact that Ya'akov knew it was Yosef because he remembered the last sugya they were last learning prove that Yehudah was sent to setup a yeshiva?   

R' Michel Yehudah Lefkowitz (and I later found it in Ohr Yahel as well) explains that a person whose first question about his son is, "Does he know what sugya were we last holding in?" is a person whose whole world revolves around nothing but Torah.  We remember things by what stands out as important to us.  For Ya'akov Avinu, what stood out about Yosef, the one thing he had in his mind about his son and what he was sure his son would have in mind about him, is the sugya they were last holding in together.  For such a person, it's not important whether his house in Goshen would have a one or two car garage -- he didn't need to send a remodeling team down ahead of time to make sure the kitchen counter had the right shade of granite and the basement was finished.  What such a person obviously needs (hence the proof of the Midrash) is to make sure his future home is a makom Torah.