The New Law «written not on tablets of stone but on tablets that are hearts of flesh» ( 2 Cor 3,3)
My brethren, consider the great mystery of the harmony and the difference of the two Laws and two peoples. The people of old celebrated Passover, not in the full light of day but in the shadow of that which was to come (Col 2,17), and fifty days after the Passover celebration… God gave it the Law written by his own hand on Mount Sinai… God came down on Mount Sinai in the midst of the fire, striking with terror the people who were standing far off, and with his finger he wrote the Law on stone, not in the heart (Ex 31,18). On the other hand, when the Holy Spirit came down to earth, the disciples were all assembled together in the same place and, instead of terrifying them from the height of the mountain, he entered the house where they had gathered (Acts 2,1f.). From the heights of heaven came an enormous noise like that of a strong wind approaching, but this noise did not frighten anybody.
You have heard the sound, see the fire, too. For on the mountain these two phenomena are to be distinguished: the noise and the fire. On Mount Sinai the fire was surrounded by smoke, but here, to the contrary, it has a shining clarity: “There appeared to them tongues as of fire, which parted.” Was this a fire that stirred up fear? Not at all: “they came to rest on each one of them”… Listen to this tongue speaking and understand that it is the Spirit that writes not on stone but in the heart. Therefore the “Law of the Spirit of life”, written in the heart and not on stone, this Law of the Spirit of life which is in Jesus Christ, in whom the Passover has been celebrated in all truth (1Cor 5,7), “has set you free from the Law of sin and death” (Rm 8,2).
St. John Vianney