When you flick off a switch, you disturb the field and the light goes out. What happens here affects there. The Fire Within the Eye'' was my only companion on a series of bicycle trips this summer through western Massachusetts. As the book, strapped to my rear rack, faded under the pounding of the sunlight, it became clear to me that light is a thing. But, stopping to read ''Fire'' at a farm stand in Sunderland, I learned from Park why the air shimmers over the superheated tobacco fields.
Light is a quality, a wiggle.
When a rainbow sprang from the mists of a waterfall in Montague, I flipped pages for an explanation. I found six different theories, with lovely diagrams, from Aristotle to Descartes and Newton. Particles, bouncing about mathematically, explain rainbows better than waves do. But then I read why I could hear trucks rumbling toward me from around the bend, but could not see them. Sound waves, being longer, take corners better than light waves.