This week's Parsha begins with Paroh having two similar dreams, the details of which are described in the Torah (בראשית מ"א:א'-ז') Later, when Paroh retells his dreams to Yosef, he leaves out certain details, and uses different words (שם י"ז-כ"ד). Rabbi Shimshon Raphael Hirsch asks why this is done, and he also asks why the חרטומים, the magicians of Paroh, who might have been wise men, could not understand the dreams. Although the first question remains difficult, the answer given to the second question is that the details left out by Paroh were essential. Without them, the magicians could not interpret the dreams, and Paroh thus needed the help of Yosef who had Hashem's help.
In the dream itself, Paroh was standing "על היאור," at the Nile River (שם פסוק א'). But in his description, Paroh says that he was standing "על שפת היאור," on the side of the river, and the river was merely scenery (שם פסוק י"ז). In truth, however it is the Nile that is very essential to the dream, as the Nile is extremely important for Egypt's survival, which the dream indicates was being threatened. Moreover, the good cows in the dream are described as "יפות מראה ובריאות בשר," good to look at and healthy of flesh (שם פסוק ב'). In his description, however, Paroh calls them יפות תואר, beautifully formed (שם פסוק י"ח), but leaves out the fact that they were healthy in terms of eating. Butchers, however, never look for beauty in an animal, only for whether or not the animal is good for eating; so when Paroh says only that the cows were good to look at, the חרטומים could have guessed many things, all of which may not tell anything about food, which is one of the main messages of the dream. We find the same problem with regards to the thin cows. The Torah originally says that they were "רעות מראה ודקות בשר," bad to look at, and of little meat (שם פסוק ד'), but Paroh in his description says only that they were דלות, needy, and "רעות תואר," "badly formed" (פסוק י"ט שם). He also doesn't mention the fact that the bad cows first placed themselves next to the good ones. By not mentioning that, it can perhaps be assumed that the bad cows placed themselves next to the good ones only because there was no pasture left in the meadow. The bad cows obviously made a much stronger impression on him than the good ones did, because he details their bad qualities in order to describe the impression they made on him. But he does not properly describe the relationship between the bad looking cows and the good looking cows which also is an important factor in the dream. As a result of these important details which are either missing or changed in Paroh's report, his חרטומים were unable to interpret the dreams; only Yosef, guided by Hashem, could do so.