This wonderful discussion by Bret Victor encapsulates a great many ideas I’ve tried to apply in my own graphics and designs. Worthy of Edward Tufte, and that’s saying something. I’ve done a few spreadsheets with active controls over some of the charts, so that users can interactively choose which parts of the data to highlight, while still seeing the context of the rest of the data. And I’ve tried to write explanations that get across the interactions between different choices, the multiple dependencies that make simple black-and-white arguments specious. But I’ve never made that kind of thinking as clear as Victor does here. Impressive.