The conceptual DNA of every modern PKM tool traces back to a 1945 essay in The Atlantic. The journey from Vannevar Bush's hypothetical desk to your Obsidian vault spans eight decades, several false starts, a deliberate simplification that conquered the world, and a recent course correction that finally approaches the original vision.
The Memex (1945)
Vannevar Bush, science advisor to President Roosevelt, published "As We May Think" in July 1945. He described the Memex: a desk-sized device storing microfilmed documents that a user could link together in "trails" of association. The key insight was that human thought is associative, not hierarchical. Bush envisioned following trails of linked material, annotating them, and sharing them with others. The Memex was never built, but it established the conceptual framework for everything that followed.
Ted Nelson and Hypertext (1963)
Ted Nelson coined the term "hypertext" in 1963 (published in 1965) and began designing Project Xanadu, an ambitious system with bidirectional links, transclusion (embedding content by reference), version tracking, and micropayments. Xanadu was never fully completed, but Nelson's ideas defined the aspirational ceiling for linked information systems.
The Mother of All Demos (1968)
Douglas Engelbart demonstrated NLS (oN-Line System) at the Fall Joint Computer Conference in San Francisco. In 90 minutes, he showed real-time collaborative editing, hyperlinks, a mouse, video conferencing, and windowed displays. This was the first working hypertext system, years ahead of its time.
NoteCards and HyperCard (1985-1987)
NoteCards, developed at Xerox PARC by Frank Halasz and others (1985), introduced typed links between card-based information units. Apple's HyperCard (1987) brought hypertext authoring to consumers; anyone could create stacks of linked cards without programming. HyperCard was enormously influential but was discontinued by Apple in 2004.
The World Wide Web (1989)
Tim Berners-Lee created the World Wide Web at CERN, implementing a deliberately simplified version of hypertext: one-way links, no transclusion, no link types, no versioning. This simplicity was the Web's great strength (anyone could create a page and link to anything) and its great weakness. One-way links break when targets move. There is no way to know what links to a page. Bush's bidirectional trails were sacrificed for universal accessibility.
The PKM Renaissance
Modern PKM tools finally realize significant parts of Bush's vision. Obsidian, Roam Research, and Logseq implement bidirectional links (seeing what links to a note, not just from it). Block references approximate transclusion. Graph views visualize the network. The 75-year arc from Memex to Obsidian is the story of an idea that was right from the start, simplified for mass adoption, and now being restored in tools designed for serious knowledge work.
The Agentic Memex (2026-)
Bush's original Memex was framed as a passive archive — a mechanized private file and library that a human would consult. YB's 2026 essay "Revisiting the Memex" argues the contemporary memex has crossed a threshold: paired with LLM agents reading the vault, it functions as a collaborative partner rather than a storage device. The hardware remains trivial (markdown files, cron jobs, text editors); the differentiator is the compounded personal context that lets the agent behave in ways aligned with its user.
The agentic memex architecture, as it has crystallized across the practitioner community:
- An agentic constitution — the orientation file every agent task reads first
- Subroutines — specialized agents/skills with defined jobs (vault hygiene, reading processing, synthesis)
- Knowledge Work PRs — agents propose changes; humans review and merge
- Heartbeat/cron triggers — scheduled invocation rather than always-on agents
- The vault as substrate — not the human's external memory alone, but the agent's context source
This is the 2026 completion of an arc Bush sketched in 1945: associative linking (the Web got most of it), bidirectional trails (Obsidian got the rest), and a partner that can traverse them with you (agentic memex).
Key Points
- Bush's Memex (1945) established associative linking as the conceptual foundation of knowledge tools
- Nelson coined "hypertext" (1963) and envisioned bidirectional links, transclusion, and versioning
- Engelbart's 1968 demo showed the first working hypertext system
- The Web (1989) deliberately simplified hypertext to one-way links, sacrificing Bush's bidirectional vision
- Modern PKM tools (Obsidian, Roam, Logseq) finally restore bidirectional links and approximate transclusion
Open Questions
- Is Nelson's full Xanadu vision (transclusion, micropayments, versioning) achievable, or is simplification always the path to adoption?
- Could the Web itself be retrofitted with bidirectional links, or is that ship permanently sailed?
- How close are current PKM tools to the complete Memex vision?
References
- Bush, V. (1945). "As We May Think." The Atlantic
- Nelson, T. (1965). "Complex Information Processing: A File Structure for the Complex, the Changing and the Indeterminate"
- Hypertext (vault note)