Maybe the burning bush was burning all the time and Moses didn't notice. Maybe the miracle is when you stop and pay attention.
We may enjoy an experience of God that is so delightful that we may think all our troubles are over and we have at last completed the journey.Then after a few hours or a few days we find ourselves on the spiral staircase again and cannot even remember the pleasures of that transient experience of divine union.The whole purpose of this alternation is to bring the soul to the total transformation of love.