The classics haven't changed, though. Many people could not read or write in those days. They just practised the formulas, learning by experience and repetition, not asking questions, trusting the Master. That is how I learned from White Cloud, and how I started teaching. Now I've taught in the west for over twenty years, with workshops and group seminars.
Westerners have intellectual appreciation for theory.
I have the benefit of feedback from my own direct students and over 700 Healing Tao instructors and their students. So we evolve and adapt. I learn from my students. The material is the same, just the delivery changes. Interpretation also changes, as modern science tells us things about the energy-field that ancient Taoists knew but did not have the vocabulary to explain and anyway wanted to keep secret.