Parashat Miketz begins with a description of Pharaoh's dreams, which Yosef will ultimately interpret as heralding the onset of seven years of surplus, which will be followed by seven years of drought. Pharaoh dreams of seven lean, emaciated cows devouring seven sturdy, healthy cows, as well as seven withered sheaves of grain "eating" seven robust sheaves. This vision, Yosef explains to the king, symbolizes the "lean" years of famine that will overtake and "devour" the seven years of surplus. The Torah describes the seven healthy cows in Pharaoh's dream as "yefot mar'eh u-vri'ot basar" – "handsome and sturdy" (41:2). Rashi, commenting on the first of these two terms ("yefot mar'eh"), explains that the cows' comely appearance represented the seven years of plenty, during which people appear healthy and content and are able to act generously towards one another, rather than competing over the limited food resources.
Rav David Pardo, in his work on Rashi's commentary, "Maskil Le-David," takes note of Rashi's comments to this verse and quips, "Yosef Ha-tzadik already preceded him in interpreting this dream!" Meaning, why did Rashi find it necessary to inform us already at this point of the symbolic meaning behind the healthy appearance of the first set of cows in Pharaoh's dream? Why didn't Rashi let the reader wait another several verses until he hears from Yosef himself the underlying symbolism of the healthy cows?
Professor Nechama Leibowitz z"l resolves this difficulty by carefully reading Rashi's interpretation of a previous instance of this expression, "yefei mar'eh." Earlier, in Parashat Vayetze (29:17), the Torah describes the matriarch Rachel with two expressions – "yefat to'ar" and "yefat mar'eh." Rashi there (in most editions of Rashi's commentary) explains the difference between these two descriptions: "'To'ar' refers to the form of the face… 'mar'eh' is a radiant countenance." Rashi appears to distinguish here between two different features of appearance: physical features, and a more general, abstract form of attractiveness and charm. "Yefei to'ar" refers to comely physical features, whereas "yefei mar'eh" denotes a less tangible aura of beauty and radiance.
Based on this distinction, Professor Leibowitz explained, we can easily understand why Rashi found it necessary to comment upon the Torah's description of the seven healthy cows. The Torah employs in reference to these cows the term, "yefot mar'eh," which, according to the rule Rashi established in Parashat Vayetze, refers to a "radiant countenance," as opposed to fine physical features. How could the Torah describe cows with such a term? This question demands an immediate response, and therefore Rashi resolves this difficulty by explaining that the "countenance" here alludes to the look of contentment upon the faces of people living in a time of economic prosperity. Thus, Rashi here is not trying to interpret the dream – after all, Yosef had already done that many centuries earlier – but rather seeks to justify the use of the expression "yefot mar'eh" as part of the Torah's description of the seven cows in Pharaoh's dream.