In 1923 Kandinsky proposed a universal correspondence between the three elementary shapes and the three primary colors: the dynamic triangle is inherently yellow, the static square is intrinsically red, and the serene circle is naturally blue.
The series ▲■● represents Kandinsky’s attempt to prove a universal correlation between color and geometry; it has become one of the most famous icons of the Bauhaus. Kandinsky conceived of these colors and shapes as a series of oppositions: yellow and blue represent the extremes of hot/cold, light/dark, and active/passive, while red is the intermediary between them. The triangle, square, and circle are graphic equivalents of the same polarities.
In March 2021, I went through a fun self-imposed experiment: no emoji for 2 weeks. Not on social media, not in private messages, not even as Slack or Discord reactions. No emoticon either: the goal was to communicate without illustrations, only with words. I did a semi-rigorous (a.k.a. half-assed) diary study, taking notes on my feelings and behaviour.
Thus, I came to the conclusion that the designer of a new system must not only be the implementor and the first large-scale user; the designer should also write the first user manual. The separation of any of these four components would have hurt TeX significantly. If I had not participated fully in all these activities, literally hundreds of improvements would never have been made, because I would never have thought of them or perceived why they were important.