I've been reading on and off The Ascent of Mount Carmel by St. John of the Cross. He writes that the work of God is passive and supernatural and that of man active and natural, and that this natural activity of man is what would extinguish the spirit. The point is made again and again at various spots. It's true that when we initiate actively many thoughts and ideas, we do not hear God speaking anymore ~ we are our own obstacles again. It's through listening and waiting that God can teach us, lead us, and bring about the union with him. This is the meaning of saying that the work of God is passive.