  In Republic II (381b-c), Plato argued for the full DDI. He asserted that a god is “the… best possible” in virtue and beauty. Virtue is a perfection of mind. Beauty is a non-mental perfection. So Plato's examples are probably meant to do duty for all mental and non-mental perfections, i.e. all perfections simpliciter. If a god is already the best possible in these respects, Plato reasoned, a god cannot change for the better. But being perfect includes being immune to change for the worse — too powerful to have it imposed without permission and too good to permit it. Thus a god cannot improve or deteriorate. Plato's argument had great historical influence. But it overlooked the possibility of changes which neither better nor worsen. If one first knows that it is 11:59:59 and then knows that it is midnight, is one the better or the worse for it? If the best possible state of mind includes omniscience, then perhaps it includes constant change in respects which neither better nor worsen God, e.g., in what precise time God knows it is. Perhaps changes to ‘keep up with’ time are required by a constant perfection, his omniscience. At 11:59:59 it is surely better to know that it is now 11:59:59, and then at midnight it is better to know that it is now midnight. Plato's argument does not rule out such changes.