The only thing that is unchanging is what is graspable by the intellect. The physical universe, by contrast, is always changing. Nonetheless it is marvelously organized and stable in its motions. It must therefore be the result of intelligence and goodness, and its order and stability the result of being a copy of something that is unchanging, an ideal pattern that is graspable by the intellect. This pattern is Plato's famous world of Forms.
