A design system grammar
Daniel Eden describes a well crafted pattern library:
One of the most appealing things about defining a pattern language or design system in this way is the flexibility that it affords. For novice builders who just need a high-level component or concept of their project, they can find it at the top of the heirarchy and use the component as it comes. For those pioneering new experiences or experimenting beyond the confines of existing produce surface, they can take those high-level components and concepts and deconstruct them into their composite parts; they can keep doing this until they have the primitive, atomic components they need to construct a bespoke pattern that still fits with harmony in the wider system.