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.

Dynamicland (#8, Bret Victor and team) puts programs on paper in a shared room. Chalktalk (#26, Perlin, He and Rosenberg) puts them on a drawn glyph that you click to run. Both make code something you point at, not something you open.

The difference worth testing is who can reach in. In a room, anyone standing there can move a page. In Chalktalk, whoever holds the pen decides.

Try it: sketch one small simulation on paper, a ball and a wall, and hand the paper to someone else. Note where they reach first, and what they change without asking.