Man's Nature is not changed through Miracles

 Moreh Nevuchim (03:32) Although in every one of the signs related in Scripture the natural property of some individual being is changed, the nature of man is never changed by God by way of miracle. It is in accordance with this important principle that God said, “O that there were such an heart in them, that they would fear me,” etc. It is also for this reason that He distinctly stated the commandments and the prohibitions, the reward and the punishment. This principle as regards miracles has been frequently explained by us in our works: I do not say this because I believe that it is difficult for God to change the nature of every individual person; on the contrary, it is possible, and it is in His power, according to the principles taught in Scripture; but it has never been His will to do it, and it never will be. If it were part of His will to change at His desire the nature of any person, the mission of prophets and the giving of the Law would have been altogether superfluous.