Reference #355: Thinking in Systems
As Gleick wrote in "Chaos: Making a New Science (1987), linear systems are modular — they can be taken apart and edit together. In contrast, non-linear systems generally cannot be added together. Doing so can create unexpected behaviour. This property of non-linearity makes it system behaviour hard to calculate and solve, but also creates rich behaviour not present in linear systems.
Meadows. Thinking in Systems, 2008. (91)