It's one of the more famous pictures in the Torah. Old man Yaakov, striken with blindness, sitting on his deathbed with his hands crossed over the heads of his two most favorite grandchildren. [Aside: Doesn't Yaakov seem to be repeating the mistake he made with Yosef, by not only raising Ephraim ahead of Menashe, but by raising the two of them ahead of all the other older, cousins.)
Only at least one great Rabbi saw the scene differently. According to the standard translation Genesis 48:14 says this*
And Israel stretched out his right hand and laid it on the head of Ephraim, who was the younger, and his left hand on the head of Manasseh, crossing his hands (for Manasseh was the firstborn).But at least one Spanish rishon sees it differently. Acording to Jonah ibn Janah the verse is not telling us the Jacob switched his hands. Its telling us how Yaakov figured out that Menasha was the bechor. Remember two things (1) By now, Yaakov is blind (Gen 48:10) So how does Yaakov know which of the two boys in front of him is Menshe? Also (2) We're not sure Yaakov ever met Menashe or been told that he's the oldest son, so how does Yaakov know which of the two boys (that he can't see) is the oldest son?
The answer is in verse 48:14. According to ibn Janah the verse is telling us Jacob has deduced from the position of the two boys in front of him which is Menshae, and which is the oldest, as he guessed (correctly) that the first born would be on his right. Ibn Janah reads the verse this way:
And Israel stretched out his right hand and laid it on the head of Ephraim, who was the younger, and his left hand on the head of Manasseh, because he had realized based on what Yosef had done with his hands [ie how Yosef placed the boys] that Manasseh [who had been placed on his right] was the firstborn.The innovations here are as follows:
(1) את־ידיו refers to Yosef's hands
(2) שכל tells us that Yaakov figured something out based on Yosef's hands; and
(3) כי מנשה הבכור tells us what exactly Yaakov figured out
Notably, this reading does not say that Yaakov crossed his hands. It merely tells us how he knew which son was which. It's possible he asked the boys to switch places. The Torah doesn't say.
*וישלח ישראל את־ימינו וישת על־ראש אפרים והוא הצעיר ואת־שמאלו על־ראש מנשה שכל את־ידיו כי מנשה הבכור׃
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