To reach that ultimate goal as predestined by God b. It's used to describe Jesus on the Mount of Transfiguration - cf. Here we learn the object of our transformation, which is to become like Christ 2. This phrase suggests that our transformation is progressive a. It does not happen all at once, but gradually b.
Transformation therefore involves a growth process a.
In which changes are taking place b. We must remember the context of Paul's words to appreciate his point a. He had alluded to how Moses out of necessity put a veil on his face when speaking to the people - cf. For when Moses had gone to Mount Sinai to receive the commandments of the Lord, being in the presence of God made his face shine brightly - cf. Thus the Christian life is to be one of contemplation, if transformation is to take place a.