If the divine nature had been converted into the human, or the human into the divine, there would have been a change—but they were not. The human nature was distinct from the divine nature. Therefore there was no change. A cloud over the sun makes no change in the the sun. Just so, though the divine nature is covered with the human nature, it makes no change in the divine nature.
-Thomas Watson
This excellent quote shows that this might be a Platonic-like concept.