Of course nothing is “too hard for the Lord.” But if we choose to apply this principle so extravagantly and harshly in our capricious imaginations, we may then make out God to have done anything we please, on the ground that it was not impossible for him to do it. We must not suppose, however, because he is able to do all things, that he has done what he has not done. But we must inquire whether he has really done it. God could, if he had liked, have furnished humankind with wings to fly with, just as he gave wings to kites. In one sense there will be something difficult even for God—namely, that which he has not done—not because he could not but because he would not do it. For with God, to be willing is to be able and to be unwilling is to be unable; all that he has willed, however, he has both been able to accomplish and has displayed his ability—Tertullian