Recent technological advances such as microprocessors and random-access memory have had a significant role in gathering, storing and processing digital data, but the basic principles underpinning such data management were established in the century preceding the digital revolution. This paper maps the emergence of those older technologies to show that the logic and imperative for the surveillance potential of more recent digital technologies was laid down in a pre-digital age. The paper focuses on the development of the data point from its use in punch cards in the late 19th century through its manipulation in ideas about correlation to its collection via self-completion questionnaires. Some ways in which medicine and psychology have taken up and deployed the technology of data points are used as illustrative exemplars. The paper concludes with a discussion of the role of data points in defining human identity.