55 - External Models are models we build up outside of our mind because of the limiting factors involved in memory. These models can be referenced during special events (e.g. Ray Dalio Archetypes) or just at infrequent intervals. If you end up using the model often, then it will naturally become internalized (memorized).
The zettelkasten is well suited for building external models, as its gives you a permanent structure and reference point as the model gets built up over a long period of time. Reason for this is that you don’t come across all the relevant information in a single block of time, for example see timeline (#excise).
When a section of notes reaches critical mass, you use them to aid with a piece of writing (blog post, research paper, book, etc). In the same way, when an external model reaches critical mass, you have two options. The first option is to leave it be and just reference it when presented with a related problem. The second option is to memorize it so that it becomes an internal model that you can use in your everyday life.