The sun is constant—every day the same fiery ball rises in the sky. But the moon cycles through constant change—one day it is whole, then it wanes until it has disappeared altogether. Yet, then it is renewed, reborn out of nothingness.
So too, we learn and progress by quantum leaps and bounds, yet the timeless, constant wisdom of Torah doesn’t budge from its place. On the contrary, the more we move forward, the deeper we fathom the truths behind us.