Why Category Theory is Uniquely Meta-Reflective

Category theory allows you to walk up and down abstraction levels using the same constructions.

It’s self-similar:

Categories have morphisms

Categories themselves are objects in Cat

Functors are morphisms in Cat

Natural transformations are morphisms between functors

This continues into 2-Cat, n-Cat, ∞-categories

You can model structure about structure without leaving the language of categories.