In the old days, Christmas lights had come in short strings that were wired serially. If a single bulb burned out or even just loosened in its socket, the circuit was broken and the entire string went dark. One of the season's rituals for Gary and Chip had been to tighten each little brass-footed bulb in a darkened string and then, if this didn't work, to replace each bulb in turn until the dead culprit was found. (What joy the boys had taken in the resurrection of a string!) By the time Denise was old enough to help with the lights, the technology had advanced. The wiring was parallel, and the bulbs had snap-in plastic bases. A single faulty light didn't affect the rest of the community but identified itself instantly for instant replacement . . .