This essay considers the actual and metaphorical power of the lightning's flash. As a natural phenomenon repeatedly described by Romantic writers, its startling, sudden illumination was repeatedly invoked by the pioneers of flash photography who looked to find suitable language in which to convey their new-found power to light up darkness. The sun already provided a vocabulary in which to describe daytime picture-taking; the associations with awe, danger, revelation and grandeur that lightning provided were readily adopted by such practitioners as Adolf Miethe and Johannes Gaedicke, inventors in 1887 of “Blitzlichtpulver,” or “lightning light powder.” But as I show through a close examination of nineteenth-century flash photographs, especially those of Jacob Riis, the characteristics of this medium are significantly dissimilar to the effects of lightning. This technology of visibility produced light that dazzled and lit up surfaces, rather than providing illumination in any deeper sense. Its literature looked to associations optimistically taken from lightning's status within European romanticism, but it could not sustain them. These photographers and inventors borrowed this vocabulary to promote their originality and inventiveness: ultimately, it allows us to identify what is distinctive, not contiguous, in flash photography's relationship to lightning.