In many translations of the Tao Te Ching, the word "Master" is used instead of sage (my very favorite is the Stephen Mitchell translation - transcendent!!). Not just a wise person, but someone in whom lives the yin and yang, and has thus mastered the essential underlying creative force. The Tao that can be named is not the Tao, because whatever it is that the human mind can wrap words and philosophies around is already something less than the Tao. It has already been reduced to ordinary human definitions, and so it cannot be the Tao. The Tao cannot be constrained by anything as mundane as words or philosophies.
I think understanding Taoism, or yin and yang here, goes back to "Love is a Force of Nature." You can't simply piece together the details of this movie and come up with a whole. You can't assign yin to one character and yang to another and feel the love between Jack and Ennis. The 'Force" here, love or tao, is an amazing synthesis of many elements culminating in an experience, NOT just a story or idea. It's not just black hat/white hat. It's the two hats on top of the two heads of the two specific individuals in this story with their two hearts and the underlying energy that connects them in love. That to me is the force - the tao - the thing that we felt when we watched this movie. And you can't disect every element and find where that lies.
The invitation to me of the Tao Te Ching is to consider how to return to the essence of life at every turn. To strip away too much thinking and too much feeling and too much doing, and just let the original, eternal quality of a thing emerge. And I think that's what so much of BBM is, and why it's such a simply crafted movie. Instead of adding layers of complexity to the story for depth, Ang Lee and Annie Proulx both, continually strip away everything that isn't the essential story. And the more you strip away, the more the force of love emerges because it's not clouded over by everything else.
Y'know...it's like the end of the movie. Ennis has nothing, is nothing, and all that's really left of him, for him, is his love for Jack. Strip away everything else, and the underlying generative force is all that's left...