It's really very simple. Math is a self-study subject. The axioms and relationships are described on paper in very clear language. How to reason and internalize

It's really very simple. Math is a self-study subject. The axioms and relationships are described on paper in very clear language. How to reason and internalize those axioms is entirely up to the reader. Each mathematician or practitioner builds their own models and tools to absorb the content. Princeton publishes a Mathematics Companion. It's a good book that covers a wide range of topics. The treatment per topic is rather brief and acts as a gateway into deeper study.