In this week's Parsha, after telling us that Yosef brought his two sons to Yaakov, the Torah says, "ויברך את יוסף ויאמר...," "And he blessed Yosef and said...." (בראשית מ"ח:ט"ו). The blessing that Yaakov gave Yosef at that moment, however, was not actually addressed to Yosef at all, but rather to his two sons, Ephraim and Menasheh. Why, then, does the Torah say that Yaakov blessed Yosef, when in fact he blessed only his sons?
The answer is that the Torah wanted to teach us that the greatest blessing a parent can receive is the wish that his or her children should take after him or her and become good people. Every parent wants only the best for his or her children, and hopes to raise them in such a way that they will emulate the parent's own positive attributes. When Yaakov blessed Ephraim and Menasheh, he therefore said "ויקרא בהם שמי ושם אבותי אברהם ויצחק," "let my name and the name of my fathers, Avraham and Yitzchak, be carried on by them" (שם פסוק ט"ז). Yaakov was thus blessing his grandchildren that they should follow in the footsteps of their illustrious ancestors. This is the greatest blessing that Yosef, their father, could possibly have received, because he undoubtedly would feel proud of sons who would live up to this blessing. Every one of us should plan to give this greatest of all blessings to our parents by being the best people we can be and living up to what our parents hope for and expect of us.