Visual Category Theory Brick by Brick: Diagrammatic LEGO(R) ReferenceCategory theory abstractions are very challenging to apprehend correctly, require a steep learning curve for non mathematicians, and, for people with traditional nave set theory education, a paradigm shift in thinking. The book utilizes a novel approach to teach category theory and abstract mathematics in general by using LEGO(R) bricks. This method was discovered when applying the same technique to teach machine learning, its data structures and