Paul Otlet was an information scientist working in the late nineteenth and early twentieth centuries. He designed various systems of cataloging and connecting information, including systems that expanded upon those are broadly used today (for example, Otlet's Universal Decimal Classification significantly expanded on the Dewey Decimal System). Among Otlet's credits are the inventions of the term "link" for the notion of documents referencing each other, and his vision of a rÃ©seau ("web") of human knowledge. From a Boxes and Arrows article on his achievements:
In 1934, years before Vannevar Bush dreamed of the memex, decades before Ted Nelson coined the term "hypertext," Paul Otlet envisioned a new kind of scholar's workstation: a moving desk shaped like a wheel, powered by a network of hinged spokes beneath a series of moving surfaces. The machine would let users search, read and write their way through a vast mechanical database stored on millions of 3Ã—5 index cards.
This new research environment would do more than just let users retrieve documents; it would also let them annotate the relationships between one another, "the connections each [document] has with all other [documents], forming from them what might be called the Universal Book."
Otlet, together with Henri la Fontaine, created the Mundaneum in 1910, in an effort to gather and classify all world knowledge. The Mundaneum was to be the heart of a "city of the intellect," and sought to break human knowledge down onto 3x5 cards, which would be cataloged using Otlet's Universal Decimal Classification.
Read more about Otlet in an excellent article on Boxes and Arrows.