This talk explores a lost history of technological failure. It examines how people from the late-18th to the early-20th centuries understood machine failures as a problem of the self — a problem of the kinds of people that failing machines created, or threatened, or presupposed. The modern period saw the rise of a public theater of machines, whose proper functioning underwrote conquest and commerce, vouchsafed privileged knowledge, and furnished powerful, enduring metaphors for nature, politics, art, and the body. Because machines provided theaters of proof for the forms of social and political life built around them, their failures threatened the social and political orders they served. For all the large-scale disruptions that failing machines foreshadowed, though, contemporaries framed some of their most pressing worries around small-scale concerns about the self, and specifically about what kinds of people we are (or should be) in the face of failing machines. From French Revolutionary anxieties about the failure of the guillotine, through Victorians’ nervous obsession with railway accidents, to factory breakdowns in Jazz-Age America, this talk excavates the largely-forgotten sources, settings, characters, and concerns that linked selves and social orders to the problematic workings of technology. Linking those developments to our own worries in the early-21st century, the talk encourages us to see the history of modern technology not just as a social history of mechanisms and devices, but as a cultural history of the self and the social orders it made possible.