Yaakov reaches out to his grandsons, Ephraim and Menashe, and blesses them with a strange blessing. Rather than granting them or praying that they receive specific benefits like wealth, peace, a strong relationship with God, and the like, he tells them that they themselves will become a blessing: "Through you shall Israel bless [their own children in the future], saying, 'May God make you like Ephraim and Menashe'." 

But since we really know nothing about Ephraim and Menashe, who both never utter a single reported word in the Torah, whose lives remain entirely mysterious to us, what are we wishing for our children? And if, as Yaakov emphasizes in this scene, Ephraim the younger will overtake Menashe the elder, why not bless our children that they should grow to be like Ephraim alone, rather than also like Menashe, who was second-best?

I heard an answer I really like, but I've forgotten where I heard it, so let me know if you know whose idea this is: For most of history, brothers have competed and fought, with the results often approaching murder (Yosef and his brothers, Yaakov and Esav) or even reaching that point (Hevel and Kayyin). The envy and hatred grows especially bitter when, as often happens in Bereshit, the younger overtakes the older.

Yaakov sees that Menashe and Ephraim, who experienced a similar reversal of blessings, do not react with the usual bitterness and violence -- instead, both seem to accept their position, valuing their brotherhood over winning. Perhaps that is why they are the model for blessing, and why Yaakov includes them both -- "May God make you, our children, like Ephraim and Menashe, boys who valued each other and their unity over personal triumph." Amen!