A map must first be legible. This means that the map must not over-compress the information of the system. It must also exist in a form that can be understood by those who will implement a system, whether that is in a diagram, a document, a software representation, or some other form. Like the map of a territory, a good architecture must be usable as a form of navigation for those who wish to build or maintain the system.
Albert Korzybski wrote about the ideas of maps and territories in mathematical semantics in his early 20th century paper. There have since been many versions of ideas like this. Similarly, this principle a loose interpretation of the idea that a system could be represented as a Category in Category Theory. In Category Theory, a functor is the morphism of one category to another, and thus leads to the idea that a well-structured architecture should behave like a category and be “functorizable”.