Genesis 41:2

and, behold, from the river came up seven oxen good-looking and fat-fleshed; and they grazed in the midst of the sedges.

AND BEHOLD, THERE CAME UP OUT OF THE RIVER. Since the land of Egypt is irrigated by the river, and it is from the river that abundance or famine befalls them, the king saw the cows coming up out of the river. The cows symbolize plowing, and the ears of corn symbolize the harvest, just as Joseph said, in which there shall be neither plowing nor harvest. He saw that the river rose only slightly and there would thus be no plowing, and the little which will be planted in moist places, a wind blowing from the east, a wind from the Eternal would burn them, even as he saw the ears of corn parched with the east wind.
It would appear to be implied in the verses that the abundance was only in the land of Egypt, even as it said, Seven years of great plenty throughout all the land of Egypt; likewise the verse, And he stored up all the food of the seven years which was in the land of Egypt. But the famine, on the other hand, was in all the lands. And so did Joseph interpret it when he said, And there shall arise after them seven years of famine, and did not mention the land of Egypt. It was for this reason that in the other countries they were unable to store up food even if they had heard about it, as they undoubtedly did, for the matter was well known throughout their lands. Perhaps this was alluded to in the dream since with respect to the fat cows, it mentions, And they fed in the reed-grass, for it was there in Egypt that they fed and stood, but the lean ones, after they consumed the fat ones, walked to and fro through the earth, and Pharaoh did not know where they had gone.

והנה מן היאור עולות, it is a common practice to water all the animals at the same time after which they all return to graze in the meadows. [as opposed to what occurred in Pharaoh’s dream. Ed.]

באחו, a place where herbs grow as we know from Job 8,11 ישגא אחו בלי מים, “can bulrushes grow without water?”

והנה מן היאור עולות שבע פרות, this was part of the interpretation, as in Egypt the river Nile rises annually above its embankment irrigating the farmland surrounding it. The cows both pull the ploughs and thresh the grain after it has been harvested. [thus far the dream reflected a well known reality in Egypt and it is difficult to see how the Egyptian wise men could have missed something so simple unless their eyes had been blinded by G’d. Ed.]

ותרעינה באחו, as they found plenty of grass near at hand.

והנה מן היאור, “and lo, out of the River (Nile)” seeing that famine and satiation have their origin in water, (irrigation or lack thereof of the earth) this was the symbol shown Pharaoh in his dream. (B’reshit Rabbah 89,4)