What determines who is, and who isn't a true master of Yoga? Is the dedication to the practice the determining factor? Is it the skill of the pose? Is it the depth of the twist or fold? Is it the physical stamina?
Certainly all of these traits are impressive and have some importance in evaluating a person's yoga practice. Yet, I think that true mastery is best seen in the apathetic yoga practitioner- the one who truly doesn't care one way or the other.
Think about it for a moment. Suppose you are in a yoga pose. Say you are in Janu Sirsasana pose - head to knee pose. For some people this is an easy pose - for others (like me) it's a challenging pose. Regardless - you're in the pose. And when in the pose, nearly everyone has his or her own individual thoughts about the pose.
If the pose is easy for you, then you may be thinking to yourself - "This is easy, I'm so skilled at this and I'm delighted that I can do this pose so well - I love, love, love this pose. How great that I can feel my back and legs release in this pose. Janu Sirsasana - YAY!"
If the pose is hard for you, then you may be thinking to yourself - "Darned this pose! It's so hard. The back of my leg is killing me. How can people ever relax in this pose? It's so frustrating. When is this going to be over? I hate this pose."
Then, you have the Apathetic Yogi. He/she doesn't care if she's in the pose or not. The pose is neither easy nor hard. The pose doesn't stir up emotions of any sort. The Apathetic Yogi's mind is completely and utterly detached from the pose. There is no longer any "gripping" of the mind with the pose. The Apathetic Yoga couldn't care if he/she stayed in the pose for another hour - or never did the pose again for the rest of his/her life. It doesn't matter what the pose is or isn't to this yogi. What matters most is that his/her mind is free from desire and/or aversion. The mind is free. The pose is merely the seat (literally - the asana) where the mind can rest.
This is mastery. Apathy is a signpost on the path to Mastery. When you find that you just don't care what pose you're doing or not - then perhaps your practice may have just taken a giant leap in the right direction.