Flow systems have two basic features (properties). There is the current that is flowing (for example, fluid, heat, mass, or information) and the design through which it flows.
Lines slip easily down the accustomed grooves. The old designs are copied so glibly that we are half inclined to think them original, save for that very glibness.
There has to be irony, both in design and in the objects. I see around me a professional disease of taking everything too seriously. One of my secrets is to joke all the time