A hundred years ago our world, even the most advanced parts of it, was a much darker place, literally, than it is now. Electricity brought us brighter light than long-traditional oil, tar, candles or gas. And since then, rapid advances in technology like lasers and fibre optics have made light serve more widespread human activities and needs than merely making the darkness bright. Perhaps sometimes too wastefully bright. We've almost succeeded in turning night into day. And millions of people can never see the stars in the night sky any more.

At least in developed and developing places, light is so much taken for granted that its power as an image in opposition to real darkness has greatly diminished. The strong theme throughout the gospel of St John, contrasting light with darkness, may have lost its punch for modern people. Yet people still marvel at the rising of the sun in a new dawn. When we hear Jesus saying of Himself (today's gospel) that He came into the world as "light, so that everyone who believes in me might not remain in darkness", what does the image convey to us? What does it mean that He was heralded as a "light to reveal the Lord to the nations"?

In His appearances as the risen Lord, Jesus was somehow changed, with a new brightness and light like how His three closest disciples saw Him on Mt Tabor in His Transfiguration.