Walking in the dark is difficult, even in the familiarity of your own home. Furniture has a way of rearranging itself in the dark so that you can whack your shins a little easier. Small, sharp toys crawl out from their hiding places to park themselves in your path. Your dog or cat is stretched out on the carpet, sleeping blissfully until your foot makes contact with a tail or a paw.

At one time or another, most of us have been plunged into darkness involuntarily because of a power outage. Suddenly, we are unable to locate what we need or to accomplish any task or activity, other than catching up on our sleep. All our movements seem painstakingly slow as we grapple with the impediment of unwanted darkness. We can't remember where the flashlight is, and have to feel our way through drawer a…