What is a shadow? Nothing in itself, you might say: a mere local lack of light, in a space that is otherwise lit up. Light, which allows us to see and know the world, is the normal precondition for picturing things. Cast shadows may help us interpret a picture by indicating where light comes from and where objects stand, but if you survey art history, you find the majority of painters giving them minor parts at most. A minority, however, turns these assumptions upside down, treating shadow as the preexistent condition and light as its shock interruption.
Phil Parry is a former BBC news and current affairs reporter. He is winner of the BT Wales award for journalist of the year, BT Wales TV reporter of the year and radio reporter of the year.