As We May Think
Decades before the web, he described the link: tie any two ideas together and follow the trail.
Half a century before the web, an American engineer described clicking a link.
The big idea
In 1945 Vannevar Bush named a problem we still have: humanity produces far more knowledge than any one person can find their way through. The trouble, he said, is not making records — it is getting back to the right one. Libraries file everything in a single rigid place, by alphabet or number, so finding a thing means following one official path, and once you have found it you start over to find the next.
Our minds, Bush pointed out, do not work that way. They work by association: one thought instantly pulls up a related one, along trails worn by experience. So he imagined a machine that would do the same — let you link any two pieces of knowledge together, and then follow those links like a path.
Where it came from
He had just run America's wartime science — the office behind radar and the atomic bomb — and wrote the essay partly to ask what thousands of scientists should turn to in peacetime. His answer: build tools that extend the mind. He imagined the 'memex,' a desk that stored your whole library on film and let you weave 'trails' through it. It ran in The Atlantic in July 1945, was reprinted with pictures in Life, and was read by two young men, Douglas Engelbart and Ted Nelson, who would spend their lives making it real.
Why it mattered
The memex was never built; the machine of microfilm and levers was a dead end. But the idea inside it — that knowledge should be linked by association, and that you should be able to make and follow those links yourself — became the design of the modern information world. Engelbart's work gave us the mouse and on-screen linking; Nelson named it 'hypertext'; and in 1989 Tim Berners-Lee turned the link into the World Wide Web. Every time you tap a link and jump somewhere related, you are using Bush's idea.
An analogy
Think of a library's card catalogue versus a trail of footnotes. The catalogue files each book in exactly one drawer; to get from a book on bows to a book on the physics of springs, you walk back to the catalogue, look up a whole new subject, and find your way down again. A trail of links is different: whoever connected the two ideas leaves a thread you can follow in a single step, from any item straight to the next. Bush's machine let everyone leave those threads. Build one yourself below.
Where it sits
Bush wrote three years before Claude Shannon's 1948 theory of information gave the bits a precise meaning, and he was pushing against the centuries-old library science of classification. His 'selection by association' also looks forward: it is the spirit of search engines, of Wikipedia's web of links, and even of the 'attention' inside today's AI language models, which weigh every word against every other — association, mechanized.
Professionally our methods of transmitting and reviewing the results of research are generations old and by now are totally inadequate for their purpose.
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.
Selection by association, rather than by indexing, may yet be mechanized.
Consider a future device for individual use, which is a sort of mechanized private file and library. It needs a name, and, to coin one at random, 'memex' will do. A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.
… associative indexing, the basic idea of which is a provision whereby any item may be caused at will to select immediately and automatically another. This is the essential feature of the memex. The process of tying two items together is the important thing.
Wholly new forms of encyclopedias will appear, ready-made with a mesh of associative trails running through them, ready to be dropped into the memex and there amplified.
There is a new profession of trail blazers, those who find delight in establishing useful trails through the enormous mass of the common record.