Parshas Mikeitz begins with the Pharaoh dreaming two mysterious dreams which no one can interpret. Finally he is told that a Hebrew slave in a dungeon has some facility in interpreting dreams. He sends for Yosef who interprets Pharaoh's dream, advises him what to do about it and becomes Egypt's viceroy.
While everyone knows this story, one of the things that strikes you is that Pharaoh's dreams don't seem that mysterious. Cows and wheat clearly refer to agriculture. Lean vs healthy are not too difficult to interpret either. And the number 7 would seem to refer to a period of time. Since agriculture tends to be seasonal, the most likely meaning of the 7 is years.
While we benefit from hindsight in seeing this, it would seem as if Egypt the homeland of magicians and men who specialized in foretelling portents and dreams should have been able to conceive of the answer too. Yosef credits G-d for the answer, but it is not clear that G-d ever provided him with any answers. Various Midrashim and meforishim address this question but I would like to consider the issue from another angle.
The brothers refer to Yosef as the Baal HaChalamot, the Master of Dreams. And indeed we begin with Yosef dreaming two dreams. Then Yosef encounters two more dreams in prison and finally there are Pharaoh's two dreams. Each time the dreams seem to be twinned.
The first time Yosef encounters two dreams he is happy and runs off to tell his brothers and father about them. After all the dreams suggest that he is set for a glorious destiny. His brothers instead see them as a plot to tyrannize them. Yosef sees the dreams as entirely positive and his brothers see them as entirely negative. Yaakov though takes a middle ground. He critiques the dream and yet watches Yosef for signs of its fulfillment.
The second time Yosef encounters two dreams it is in prison. One man sees himself handing a cup to Pharaoh. Another sees birds eating food off his head. This seems even easier to interpret than Pharaoh's dream. Serving wine to Pharaoh suggests a return to a position of honor and birds don't eat food off living men. Yet again it says, there is no interpreter.
When the men dream the dreams, the Pasuk says, Ish Kepitron Halomo. Each Man According To The Interpretation of Their Dream. When Yosef assures them that he can tell them the meaning he says, Halo LeElohim Pitronom. Is Not With G-d Your Interpretation?
Now either they dreamed their interpretation, in which case why would they need it interpreted or it is with G-d. And at no point is it clear that Yosef is recieving prophetic inspiration in regards to the dream, then how is it with G-d?
The Pasuk that discusses the dream is full of redundancies. First it says, VaYeholmu Halom. They Dreamed a Dream. Then it says, Shneihem Ish Halomoi. Both Each Man His Dream. Then Balaila Ehad. In One Night. And finally, Ish Kepitron Halomo. Each Man According To The Interpretation of Their Dream. What are all these extra things telling us? Some of the Pasuk seems to emphasize the unity of the dream, some the separate nature of each man dreaming a dream.
Then the Chief Baker sees that Yosef's interpretation of the Chief Vineter's dream was positive, he asks him to interpret his dream. Why assume that the positive interpretation of the baker's dream will affect his dream, unless they are one dream. And if they are indeed one dream, the Chief Baker had reason to expect a positive interpretation too.
Yet instead one dream has a positive interpretation and the other a negative one. So too in Pharaoh's dream, the dream has a negative interpretation and a positive one in the same dream. There are the seven healthy cows and healthy stalks and seven unhealthy cows and unhealthy stalks. And here too Yosef tells Pharaoh, the two dreams are really one dream.
How can two dreams really be one? To understand this and why Egyptian magicians and wise men failed to interpret the dreams of the baker, the vintner and Pharaoh; it is necessary to understand the pagan view of divinity. Pagans do not see a unity in G-d but rather divisions. One god might handle a particular function and another god another function. Even in Christianity, there are divisions in their god. At its most elemental we have dualism in which there is a god that does good and a satan figure that does evil. But there isn't one G-d from whom both what we think is bad and good stem from.
This is why no one in Egypt could interpret Pharaoh's dreams or those of his officers. They could not conceive that a dream could have foretell both bad and good because they could not conceive that what people perceive as bad and good, both comes from the same source. When Yosef proclaims that the interpretation of dreams belongs to G-d, he is really saying why he has the ability to interpret dreams, not because his knowledge of dream lore is superior to that of the Egyptians or because he sees the revelations as prophetic visions but because these dreams foretell the future and Yosef knows that what is to happen is in the hands of G-d who brings about both bad and good for a common end. Thus the different dreams are all really 'one dream' because they represent the unity of purpose of one G-d.
Yosef viewed his dreams as entirely positive and his brothers as entirely negative. In his succession as a slave and a prisoner, Yosef has come to understand that the interpretations of his dreams belongs to G-d and whatever happens to him, good or bad, is ultimately part of G-d's purpose. Understanding this gives him the ability to interpret the dreams of the baker and the viniter, and then to not only intepret Pharaoh's dreams but to then advise him what to do. What gives him the right to do that? His understanding that dreams are a succession of G-d's plan and that the dreams which hold both negative and positive events will be used to bring about G-d's salvation.
He meets the brothers who do not yet understand this with trials. The events he subjects them to helps bring about their understanding of the ultimate unity of G-d's purpose from the good and the bad we undergo. Only then can he convincingly assure them that everything that has happened to him has been part of G-d's plan and is for the best. Only once they have experienced it themselves can they believe his sincerity and understand that the coming exile of their descendants will also end in a triumphant exodus because both the exile and the redemption are 'one dream.' They are part of one promise that our one G-d made to Avraham for his one people. The dream is one as we are one as G-d is one.