On the contrary. He did understand it. However it is a fact that he had not learnt the full system and had insulted Yip Man when he asked to learn the final sets. He offered money and property, and as a result was not taught because it would not have been fair on the other students. Bruce knew that he would look bad if he claimed to teach Wing Chun from Yip Man. So he set about on his own, and as a result of this self discovery he finally ended up with something totally unique.
Isn't this the major argument that Wing Chun lovers use - Bruce Lee only discarded it for JKD because he hadn't mastered it and didn't fully understand it.
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