At midnight on December 31, 1965, Pope Paul VI pressed a button in his apart­ment in the Vatican to switch on the lights illuminating the statue of Cristo Redentor on Mount Corcovado, in Rio de Janeiro, some 6,000 miles away. The installation, planned by the prominent Ameri­can lighting designer Richard Kelly, was part of the city’s 400th anniversary celebra­tions, which included parades and festivities and, on the last day of the year, thousands of white candles and flowers along the beach, women dressed in white, and copious amounts of the “white” alcohol cachaça. Having the pope illu­minate the mountaintop statue was part of a typically Cariocan mix of the religious and political or, as one newspaper put it, progress and paganism, consecration and commerce:

At the stroke of 12 (Rio time) — Pope Paul VI touched a button in the Vatican and illuminated, with a new set of floodlamps, the figure of Christ the Redeemer that overlooks the city from atop Corcovado Mountain. Air Force planes flew overhead, dropping “silver rain” of bits of foil painted with the name of the State Bank. ¹

It is unlikely that the pope’s button controlled the electricity flowing to the lights at the base of the statue. More likely, he sent a signal to an operator situated near the switches. But by touching a button, the pope activated a virtual circuit that linked his own body to the mountaintop figure of Christ half a world away. The gesture reaffirmed — indeed, embodied — the con­nection between the Brazilian state and the Catholic Church. But it did so in dis­tinctly electrical terms: the smallest of human gestures, a touch, summoned a force of nature, instantly and across a great distance.

The new year’s eve drama in Rio underscores the ways in which the workings of electric light are resonant with divine action. First, it can be exercised from far, far away — the pope was on the other side of the Earth. It is effortless — the pope had only to touch a button (God, presumably, does not struggle in the creation of earthly events). It is instantaneous — the pope’s will, his gesture, the visual effect, and the crowd’s awe were virtually simultaneous. And, like God, electricity is unseen, known only through its effects, and historically has been most visible as one or another form of radiant light. As such, electric light recalls ancient religious iconography, despite its technological provenance. ² Light is laden with literary and pictorial tropes heavy with scriptural significance; at many points in Western religious history it has indexed the very presence of God. But rather than address such momentous matters, here I will look in a different direction: toward the button.

The light switch is part of a long history of control mechanisms that regulate an otherwise continuous flow. In this sense it is antique in conception, akin to the dams or sluices that control the movement of water. Although there is no evidence for valves in ancient oil lamps, the Roman Egyptian author Hero of Alexandria described something akin to an automatic fuel supply that worked by means of a pneumatic contrivance. ⁵ A window shade or shutter might be considered a kind of switch that controls the presence of visible light; similarly, a door controls movement between inside and outside a building or from one room to another. ⁶

Electricity, an invisible force whose operation lay outside ordinary experience, was often explained by means of a hydraulic analogy employing terms such as hydraulic head, flow rate, and pipe diameter to help students grasp electrical potential, current, and resistance. ⁷ The analogy, although inexact, remains common today.

The light switch is part of a long history of control mechanisms that regulate an otherwise continuous flow.

The English term “switch” derives from a riding switch, a long stick used to indicate to a horse the rider’s interest in greater speed, essentially to convey a rider’s will wordlessly and convincingly. Railway operators picked up the term in the 1820s to designate the set of rails used to shunt trains from one track to another; the lever an operator pulled to effect the shift was called a “switch-rod.” More generally, the switch was a means to change the configuration of a track or circuit, which facilitated its application to electrical circuits. Later in the 19th century, the term was used to describe a telegraph key; with its then unprecedented speed of transmission — as if thought itself leapt across continents — the switch-activated telegraph enabled what seemed nothing less than a compression of time and a collapse of space. By the end of the century, “switch” denoted a manipu­latable tool used to regulate potentialities within a larger current of objects or forces, most notably electricity. ⁸

Earlier forms of lighting were not so much switched on as they were prepared for illumination. Generating light from an oil lamp, for instance, required several steps — removing a protective enclosure for the flame; assuring the fuel supply; examining the wick; igniting it (no small task in the days of the tinder box, before the commercialization of wooden friction matches); adjusting the flame; and, finally, lowering the enclosure. ⁹ These steps were sufficiently laborious to preclude the use of any term suggesting an instantaneous operation. Although gas lamps were simpler to light than oil lamps, they still required a sequence of steps that had to be repeated in turn for each lamp. ¹