What was the significance of the river in the dream? Why did Pharaoh dream specifically about cows and ears of grain?
Ramban, Da'as Zekenim: Since the river constituted the Egyptians' sole water supply, abundance on the one hand and hunger on the other, depended on it. Consequently, the cows represented plowing, and the ears, harvesting. 1
Riva citing Bechor Shor: Had he dreamed only about cows, this could refer to weak nations overpowering strong ones. Had he dreamed only about ears, we would not learn about the satiation being totally forgotten. 2
Malbim: The Egyptians deified the river and believed in the power of cattle and worshipped cows 3 , for satiation and grain come from the river and cattle, these were Simanim of satiation.
Ramban: We learn this from Bereishis 45:6. See Ramban.
This is like they hold, that the bad ears merely covered the good ones - refer to 41:7:151:1 (PF).
I do not know his source that they worshipped cattle. The Torah says only Tzon (46:34)! (PF)
What is the significance of the cows' good looks?
Rashi: It signifies the years of plenty, when people look at each other with a pleasant countenance (without an Ayin ha'Ra).
In Pharaoh's dream it says "Yefos Mar'eh u'Vri'os Basar." Why, when he related the dream to Yosef
Oznayim la'Torah: As is the way of people who follow their eyes, he gave precedence to looks before beneficial use (more meat). 1 But after he was shaken by the dream, 2 he became more realistically inclined.
Ha'Emek Davar: (18): Regarding people, e.g. Rachel and Yosef, Yefe To'ar is the shape of the face, and Yefe Mar'eh is the complexion. We can say similarly about animals. The added volume due to a fetus gives a nicer To'ar to an animal (Bava Kama 49a), apart from the added meat, Yefe Mar'eh is the color. Here the good appearance of the skin alludes to success also in selling the excess grain to other countries. Below, pregnancy alludes to influence on others, just like a pregnant cow gives birth and nurses. 3
What is "ba'Achu" in which they grazed?
Rashi: 'In the marsh'.
Ramban #2: "Achu" is a mixture of grass and vegetation that grows beside the river; it is named "Achu' (from the word Achvah - brotherhood), due to the variety of grasses that grow together.
Rashbam: 'A location where grass grows'.
Targum Yonasan: "Among the reeds (canes").
Ramban: Perhaps it can also refer to the marshland (like Rashi, refer to 40:2:3:1), and the grass is called after the marsh where it grows.
Ha'Emek Davar: This was a sign that the abundance would be only in Egypt, i.e. near the river, like the Ramban said. (The Ramban learns from "b'Chol Eretz Mitzrayim" (verse 29). How can this all be near the river? Egypt is 400 Parsah (after 1600 kilometers) by 400 Parsah (Pesachim 94a)!
Why does the Torah not mention that the lean cows too, grazed there?
Why are there two expressions "Yefos Mar'eh u'Vri'os Basar", and also for the bad, "Ra'os Mar'eh v'Dakos Basar"?
Kol Eliyahu: Ra'av and Kafan are different - "b'Ra'av Padcha mi'Maves... l'Shod ul'Chafan Tischak." 1 Ra'av is when the land does not produce good grain. Kafan is when it produced good grain, but Hashem made that it does not satiate. Yefos Mar'eh u'Vri'os Basar" hints to good produce that satiates]; Ra'os Mar'eh v'Dakos Basar is the opposite in both ways.
Why does it say "from the river came out
Ohr ha'Chayim (2): The cows were created in the river. This helped Pharaoh to realize at the time that it is a dream. It also showed that the abundance and famine will be from the river.
