Seeing the face of God brings death in the old covenant; here in the new, the angel tells Zechariah’s unborn child that he is “the prophet of the Highest” and one who “goes before the face of the Lord.” John is “makes ready [God's] ways” as a crier in the dark night who carries a great torch to light the way.
God is come “to give science of health to His people, into remission of their sins,” proclaims John the Baptist. How does God accomplish this? “By the inwardness of the mercy of our God.” In other words, God’s own mercy visits us.
“And thou, child, shalt be called the prophet of the Highest; for thou shalt go before the face of the Lord, to make ready his ways. To give science of health to his people, into remission of their sins; by the inwardness of the mercy of our God, in the which [in which] he springing up from on high hath visited us.”
And this is the science of health – that God Himself visits us with mercy.