Rabbi Elazar read to report that Jacob bowed to Joseph because Joseph was in power. The Gemara read Jacob's action to illustrate a saying then popular: "When the fox has its hour, bow down to it." That is, even though one would ordinarily expect the lion to be the king of beasts, when the fox has its turn to rule, one should bow to it as well. The Gemara thus viewed Joseph as the fox, to whom, in his day, even the senior Jacob bowed down.