Big Gains
The things about Dao, Law, Supreme Law, and Extremes are not something you could literally understand by talk instead you need to practice it. And currently, he could only have touched the thin layer of the Law.
Laws are the natural rules that act as controllers rather than manipulators. Controlling the natural rules allows a person to burrow energy directly from Heaven and Earth. The Earth Rank arts work on the same principle, while spirit rank arts can form a spiritual phantom of anything user want with the help of true energy, earth rank arts borrows energy from the surrounding.
To use Law, the user needs to burrow different energy from the surrounding to form certain elements. Such as, to form Fire, one needs to burrow fire energy from the surrounding. This is the difference between concept and Law, and why does Fei need to practice Law even though his God Force is no less powerful than any kind of Law?