“What prevented Him from making His primary object a direct commandment to us, and to give us the capacity of obeying it?”

Source: Guide for the Perplexed (c. 1190), Part III, Ch.32
Context: What prevented Him from making His primary object a direct commandment to us, and to give us the capacity of obeying it?... As it is the chief object and purpose of God that we should believe in the Law, and act according to that which is written therein, why has He not given us the capacity of continually believing in it, and following its guidance, instead of holding out to us reward for obedience, and punishment for disobedience, or of actually giving all the predicted reward and punishment? For [the promises and the threats] are but the means of leading to this chief object. What prevented Him from giving us, as part of our nature, the will to do that which He desires us to do, and to abandon the kind of worship which He rejects? There is one general answer to these three questions, and all questions of the character; it is this: 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 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.