The trip back in time starts more than 50 years ago. As We May Think is an article by Vannevar Bush (*1890 †1974), that was published in 1945 [Bush 45]. During World War II Bush is Director of the Office of Scientific Research and Development and in consequence the highest-ranking scientific administrator in the US war effort. He coordinates the activities of about six thousand American scientists and is especially in charge of the Manhattan Project that develops the atomic bomb [Klaphaak 96], [Hegland 2000].
As We May Think is the description of a hypothetical system called Memex (cf. 2.1.1), that supports scientists in their daily work. Bush recognizes the situation that coping with an increasing number of scientific publications becomes a rising problem. Memex should archive all scientific journals and reports as well as all writings of the owner of the system on microfilm.
To keep track of all the data Memex offers to define trails through the stored articles. This creates sequences of pages that belong to a given chain of thought. Vannevar Bush points out, that classical filing methods like sorting by alphabetical order are artificial and do not correspond to the way humans think. A more natural approach would be to put the articles into context. A set of meaningful relations between the documents that map the associative style of the human mind.
The influence of Bush’s article on the field of hypertext cannot be underestimated. Memex’ trails count as the first sketch for the concept of hyperlinks.
Memex is designed with the scientific researcher in mind. Plenty of books, reports, magazines and newspapers are published every month. But classical methods of indexing stall at this amount of material. In As We May Think Vannevar Bush writes [Bush 45, p. 43],
Our ineptitude in getting at the record is largely caused by the artificiality of systems of indexing. When data of any sort are placed in storage, they are filed alphabetically or numerically, and information is found (when it is) by tracing it down from subclass to subclass. It can be in only one place, unless duplicates are used; one has to have rules as to which path will locate it, and the rules are cumbersome. Having found one item, moreover, one has to emerge from the system and re-enter on a new path.
Hierarchical filing is not sufficient to permanently enhance our ability to cope with the record. Bush takes the human ability of association as model to propose a better scheme. He continues [Ibid.],
The human mind does not work that way. It operates by association. With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain.
Another scheme is already in place that corresponds to human associations. As soon as a scientist gets interested in an article she might take the references as recommendations to get more material on the topic. Studying those papers leads to the next level, and so forth. During research she is forming a characteristic path through the literature. The creation of this path is the central idea behind Memex.
All articles are stored on microfilm inside the machine. They can be projected on some translucent screens on top. The user builds trails along the way of articles she reads. Two articles are connected by simply pressing a button. The entire trail is named and stored in a code book inside of Memex for later reuse. If our researcher comes across a page that is already part of another trail she can benefit from this and follow the other trail that might be related to her current interest.
Trails count as the first conception of hyperlinks. Although – considering the Web’s understanding of links – one should better say the first conception of guided tours. Trails are a sweeping concept that is on a higher abstraction level than html hyperlinks.
Fig. 2.3 This illustration is based on Bush’s description of Memex: «On the top [of the desk] are slanting translucent screens, on which material can be projected for convenient reading. […] At the bottom of each are a number of blank code spaces […] The user taps a single key, and the items are permanently joined.» [Bush 45, p. 43-44]
Browsing through the pages of a book or the pages of a trail happens with breathtaking ease. A kind of joystick is used for this purpose. Once again Vannevar Bush [Ibid.]:
On deflecting one of these levers to the right he runs through the book before him, each page in turn being projected at a speed which just allows a recognizing glance at each. If he deflects it further to the right, he steps through the book 10 pages at a time; still further at 100 pages at a time. Deflection to the left gives him the same control backwards. A special button transfers him immediately to the first page of the index.
Not enough. Annotations and authoring are also possible. Therefore the projection screens can be photographed from underneath and the page is stored on microfilm in the repository. Such pages can become part of trails like any other page.
It shall be mentioned again that Memex has never been built. But the existing technology of 1945 – microfilm, dry photography, photocells – lead Vannevar Bush to the assumption that his concept is realistic for a future not far away. His judgment regarding to the evolution of technology was wrong. But his ideas became inspiring for the development of hypertext. The book From Memex to Hypertext: Vannevar Bush and the Mind’s Machine by James Nyce and Paul Kahn [Nyce/Kahn 91] gives evidence for the profound influence of Bush’s vision.