JohnA, their are different levels of knowing, and different areas define them differently. A book I have with me now (Super Reading Secrets) identifies the levels as: awareness, familiarity, knowledge, or expertise. Many people say they know something but are only at an awareness level. There is also a proverb about learning that is a favourite of mine:
I hear and I forget.
I see and I remember.
I do and I understand.
I've used this proverb many times. I can see how it parallels my own understanding of material, while going to school and other times in life. I like to use it as a check point, whenever I say I know that.

As for the duality or polarity of the emptiness, you can try reading a book on buddhist meditation and you'll discover the becoming filled by going into the emptiness oppositions and sameness; about being empty and connecting to everything (the universe).
Master Lin presents a very simple system that is powerful. That doesn't mean it isn't founded on the richness of qi understanding, only that he does not include it in his system. Maybe for those who progress deeper, or who Do the system more the understand is revealed. Maybe he just wants people to get the most benefit with the least effort, as fast as he can help them.
You are perfection.
Iam2
