It was the ultimate memory machine: a device that would store information associatively, keeping a record of all the interconnections between ideas – but never forget things. In this chapter I tell the story of a technical ‘vision’ that has survived for over seventy years: Vannever Bush's memory extender, or Memex. Memex was an electro-optical device designed in the 1930s to provide easy access to information stored associatively on microfilm, an ‘enlarged intimate supplement’ to human memory (Bush [1945] 1991, 102). Literary and historical works routinely trace the history of hypertext through Memex, and so much has been written about it that it is easy to forget the most remarkable thing about this device: it has never been built. Memex exists entirely on paper. As any software engineer will tell you, technical white papers are not known for their shelf life, but Memex has survived for generations. What, then, can we say about a dream that has never been fulfilled, but nonetheless recurs? Memex has become an inherited vision within hypertext literature.

In 1991 Linda C. Smith undertook a comprehensive citation-context analysis of literary and scientific articles produced after the 1945 publication of Bush's article on Memex, ‘As We May Think’, in the Atlantic Monthly. She found that there is a conviction, without dissent, that modern hypertext is traceable to this article (Smith 1991, 265). In each decade since the Memex design was published, commentators have not only lauded it as vision, but also asserted that ‘technology [has] finally caught up with this vision’ (ibid., 278).