Our Lord Jesus Christ is the light of the world which shines in the darkness, per the Gospel according to St. John, 1:4-5. He is truly the very light from which all lights are lit. As the Father has eternally kindled the wick that is His Logos, so the aroma which ascends into the air is the Holy Spirit of God. In this intimate communication of pure light, an ever-loving and perfect illumination lights up the entire universe. Remember the Seven Candlesticks in the first chapter of The Revelation? Christ our Lord stands in the middle of them, lightning the three on one side and three on the other side by His eyes, skin, and hair - all burning white, light, fire, and glory.
Metaphorically, the Gospel of our Lord Jesus Christ is the height of all the readings. Those which come before are foreshadowing or remembrance, but in the Gospel our blessed Saviour speaks His own words. Whereas God speaks through St. Paul, Isaiah, David, or the Psalmist in the first (and second) reading(s), God talks to us directly during the Holy Gospel, using the lips of the deacon or priest or bishop. When God came to teach us Himself, it is far greater than going through a middle-man. He is really here!