Once the world was more thickly peopled with shadows than it is today.Cities that burn light day and night were darker then. Streets were lit with gas or oil or not at all. Moonless nights were not for unaccompanied walking. One can only imagine the welcome brightness of full moon.
Shadows would have leapt up on walls in firelight, followed behind us either faithfully or inspiring fear. Their beauty enriched childs' play and a whole genre of theatre. 18th and 19th century toys used the projection of shadow and mechanical motion to exquisite effect. Today although the time has passed for family slide shows or magic lanterns we can still make a duck or wolf move across the wall by putting our hands to work in front of a lamp or using an open umbrella as a screen.
Still architects work with both blocks of light and its absence. And when Louis Kahn was quoted as saying, "the sun never knew how wonderful it was until it fell on the wall of a building" - he might have only been half joking.
For me the most exquisite reflection on light and dark is Jun'ichiro Tanizaki's In Praise of Shadows. For him, an entire aesthetic depended on darkness. Gilded lacquer work was meant to be seen in half light, the beauty of spare rooms appreciated only by candles - the lustre of tarnish likened to an image seen on dark water. A room without shadows, he argues is merely a void. "It was different from the darkness of a road at night.It was a repletion, a pregnancy of tiny particles like fine ashes, each particle luminous as a rainbow. I blinked in spite of myself as though to keep it out of my eyes."
*shadow puppet image "borrowed" from the Indonesian National Library.