[cwhy]

Other people have given very good suggestions. But just mention that there is not any first principles for mathematics, that is an active area for research for pure math.

There are a lot of layers of mathematics, the deeper you get, the more difficult it becomes. But for normal applications (like antenna design, machine learning, electromagnetism, cryptography etc), you don't need to get to the deepest level, which are mostly proofs for a formulation of the whole mathematics framework.