"So he (Yaakov) blessed them that day, saying, by you shall Israel bless saying, may Hashem make you like Ephraim and like Menashe. And he put Ephraim before Menashe" (Braishis 48:20). Many fathers follow Rashi's understanding of the above, and on special occasions (Shabbos, yom tov, and erev Yom Kippur) bless their sons with the formula of Yaakov. Interestingly, the Targum Yonasan says that this bracha is to be extended to an infant at his bris milah. What might the connection be between bris milah and Ephraim and Menashe?
Rav Pinchas Friedman shlit"a of Belz suggests the following interesting relationship. The Sefer Parashas Drachim (drush 4) notes that Hashem judges man as he is now at this time, and does not look at the bad that the individual will do. Yet, in His abundant kindness Hashem does look to the future to see the good that the individual will do and incorporates that positively as part of present judgments.
Proof to the above may be found in the medrash (Shemos Rabbah 3:2) on the possuk (Shemos 3:7) in which Hashem said "ra'oh ra'isi - I have indeed seen the affliction of my people in Egypt. Commenting on the double expression "r'oh ra'isi", the medrash cites Iyov (11:11) - "for he knows the men of vanity, he sees the wrongdoer and does not take note." Rashi understands this possuk to refer to the extraordinary patience of Hashem who sees evil being perpetrated now, but delays judgment. The medrash understands the verse to mean that He sees bad in the future but does not consider it now. Thus you, Moshe, see the Jewish people accepting the Torah at Sinai, seeing the good in the future, which is their ticket to deliverance. I (Hashem) additionally see their sinning with the golden calf, but I do not take that into consideration.
Similarly, continues the medrash, Hashem answered Hagar and provided a well of water for Yishmael, despite the fact that Yishmael will cause many of Hashem's children to die of thirst when they will be exiled after the destruction of the Beis Hamikdash. When the angels protested to Hashem's intervention Hashem responded "right now what is he - innocent or guilty?" They responded that he is innocent. Hashem then stated that He only judges "ba'asher hu sham - as he is now".
We find that when Yosef brings his sons to Yaakov to be blessed, Yaakov asks, "who are these?" (Breishis 48:8). It is difficult to accept that Yaakov didn't recognize his grandsons with whom he had been learning for seventeen years. The Medrash Tanchuma (6) explains that while he wished to bless them, the shechina departed from him, because Yerovam and Achav were destined to come from Ephraim, and Yayhu and his sons from Menashe. Yosef prayed, and the shechina returned to Yaakov and he blessed them.
When Yosef wants to remove his father's right hand from the head of Ephraim to that of Menashe, Yaakov protests, "I know my son, I know; he too will become a people, and he too will become great; however, his younger brother shall become greater than he, and his offspring's frame will fill the nations" (48:19). Rashi again cites the Tanchuma which says that Menashe will be great, as Gideon will come forth from him, through whom Hashem will perform the miracle of three hundred men destroying the army of Midyan of 135,200. However, Ephraim will be greater as Yehoshua will come from him, who will apportion the land and teach Torah to Israel, and the entire world will acknowledge Hashem when the sun will stand still for Yehoshua.
The Arugas Habosem asks, if Yaakov is basing his blessing on their future progeny, they both have wicked offspring, and if he is blessing them based on the present, then Menashe, the bechor, should get preference? He answers that Yaakov was acting on the principle that the future good be reckoned with now and the future bad not be noted currently, and praying that Hashem would emulate his ways! This is "b'cha Yivarech Yisrael." As his grandsons are being judged upon the future, so to will the Jewish people always merit to benefit now from what their positive and glorious future has in store for them.
That Hashem looks to our future may be seen in the mitzvah of milah. The Rambam in Moreh Nevuchim understands this mitzvah as a means of helping the Jew to be moral, assisting him in curtailing his sexual drive. The Ramban sees the mitzvah in a more positive way, for the Jews to carry with pride the sign of the covenant between G-d and Israel, and the seal of the King on his body. Interestingly, be it soor meirah or assey tov, it does not apply to the eight day old infant, but rather this mitzvah is unique in that it is performed now for the future. As the father performs this mitzvah on behalf of his child's future, so does Hashem look to our future to exonerate us.
With the above principle we may understand the Talmud (Menachos 43b), "when King David found himself naked in the bathhouse, he felt melancholy, bereft of mitzvos. When he remembered his milah he was appeased." On a deeper level, suggests Rav Pinchas Friedman shlit"a, David entered the bathhouse to immerse and purify himself from sin. He did a cheshbon hanefesh and found himself without mitzvos. He was depressed, until he remembered the mitzvah of milah, which signifies that Hashem looks to the future and sees the good he will yet do, and this encouraged him.
The connection, then, of the Targum Yonasan between Ephraim and Menashe and milah is: just as milah underscores His looking into the future regarding His nation, so did Yaakov regarding his grandsons.
We can thus understand the teaching of Ben Azzai in Avos (4:3), "do not regard anyone with contempt, for there is no man who does not have his hour." Allow me to explain it referring to the potential of each individual.
Finally, the concept of future good has halachic ramifications as well. The Shulchan Aruch (Yoreh Deah 344:1) teaches that one may exaggerate slightly in a eulogy. The Taz is troubled by this license, and asks why a slight lie is permissible? His answer is very perceptive. He postulates that if the niftar performed a mitzvah such as tzedakka or chessed in a particular way, if a circumstance arose requiring greater effort and exertion, he would have done it too. Therefore we have the right to say that it is as if he already did it. We have the right to eulogize the future the niftar would have had.