창세기 44:15의 주석

'הלא ידעתם כי נחש ינחש וגו KNOW YE NOT THAT SUCH A MAN AS I CAN CERTAINLY DIVINE? — Are you not aware that so distinguished a person as I am knows how to divine, and (even though you have robbed me of the goblet by which I divine) to discover by my own intelligence and common sense or by logical deduction that it was you who stole the goblet!

איש אשר כמוני, princes and ministers were in the habit of performing magic tricks as we know from Ezekiel 21,26 where the King of Babylon is described as standing at the crossroads in order to engage in this kind of divination. Joseph is saying that he knows who stole my property.

What is this deed. It was not only wicked but foolish as well, because I am an expert diviner.

הלא ידעתם כי נחש ינחש איש אשר כמוני, "Did you not know that a man such as I is able to divine things?" With this comment Joseph wanted to answer the brothers' accusation that he had framed them, since how could he have known that they had committed the theft unless they had themselves confessed to it? Joseph headed off such an accusation by saying that someone like himself practiced sorcery.

Through knowledge, reason ... that you stole the goblet. I.e., although you stole the goblet I divine with, so how could I have known that you stole it? Common sense should have told you that, “A man like me...”

כי נחש ינחש איד אשר כמוני, “for a man of my stature surely is able to divine things?!” He meant that seeing that he was a man in an exalted position, he would investigate thoroughly if someone accused was indeed guilty of the crime he has been accused of.

The reason the Torah has Joseph describe the sorcery as being performed not "by myself," but by someone "in a high position such as I" was, that not just he but anyone who occupied high office was presumed to be able to divine things like that. The brothers should have taken this into consideration before stealing anything.