I have been moved to a different set of tasks at work which is taking much of my time, hence the light posting.
The Midrash teaches that Ya'akov rightfully should have been led down to Egypt in chains. However, Hashem had mercy; He did not want Ya'akov to suffer such embarassment. Hashem therefore arranged for Yosef to descend to Mitzrayim first, leading Ya'akov to willingly make the journey on his own accord. The Midrash ends with a mashal: A farmer could not drag his cow to market. Instead of trying to pull it with ropes, the farmer wisely led the cow's calf in front of its mother, whereupon the cow had no choice but to follow.
Two points require explanation: 1) What does the mashal add to the teaching of the Midrash that is otherwise unclear? 2) If Ya'akov truly deserved to be led into galus in chains, how could he so easily be let off the hook?
The Shiurei Da'as ("Hisgabrus HaDa'as") offers a brilliant insight. Ya'akov knew that Egypt was a center of tumah; he knew that his descent to Egypt would begin a period of exile that would last hundreds of years. Ya'akov had wanted to remain in peace in Canaan and avoid the specter of galus at all costs. So why did he go? Because for all the greatness of Ya'akov Avinu, he could not escape the emotional attachment he felt as a father for his son Yosef. For all his greatness, Ya'akov was pulled by the same instinctual draw that causes a cow to follow its calf.
Ya'akov may have escaped physical chains, but he could not escape being led by the emotional chains that bound him to Yosef. And those chains were even stronger and more powerful.