The “X” in X-ray is the semiotic placeholder that its inventor, Röntgen, gave to a new form of technical vision that could pass through the atmosphere and pierce the body to generate shadowy photographic tracings from a distance. The unknown source of this radiant energy was likened to a divine light that comes from the beyond, erasing boundaries between internal and external worlds. However the name stuck and this transcendent visuality was quickly transformed into a technology for the management and control of internal flaws and external threats. Today its penetrating rays have been re-directed to uncover malignancy in flesh, defects in nuclear reactor rods, and terrorists, via airport security screening.