Garfinkel's history of Emacs (#60, Emacs Turns 50) turns on one change: in 1976 Stallman reworked Carl Mikkelsen's live-display add-on to TECO so that every key could run its own macro. The editor became a place where you rewrote the editor while using it.

Hanacek's dyna.ink (#55) asks for something similar from a canvas: you draw, it reads your drawing back, and you accept or challenge the reading. Both put the tool's interpretation inside the loop instead of behind a menu.

Engelbart's 1968 demo (#5) is the common ancestor. Try it: pick one thing your tool does on its own, a template or autocomplete, and find out whether you can change it without leaving the work.

Bush's memex (#3, As We May Think) saved the trail you took through documents. Petricek's Histogram (#15) saves a program as the list of interactions that built it, then shows that list as code or as a spreadsheet. Same bet from 1945 and today: the path is the artifact, not the pile it passed through.

Try it: next time you reach an answer in a spreadsheet, write down every cell you touched in order, then hand that list, not the sheet, to someone else. See whether they reach the same number, and where they stop to ask why.

Chalktalk (#26) turns a drawn glyph into a live sketch you can link to other sketches: its binary tree takes a swipe to undo and a drawn curve to trigger a traversal. Crosscut (#23) starts from the same instinct, a stylus on a page that keeps the looseness of paper and gains the behavior of a model.

The Chalktalk paper is candid about what is missing: no formal evaluation, a stack and a tree that cannot yet call each other, a link type system still in research. That candor is the useful part.

Try it: draw a stack on paper and name two operations, push and pop. Then ask what a second drawing, a tree, would need to send the first for the two to explain a call stack together.