Eight Trigram Boxer
>>I guess this is just an illustration of how Bagua Zhang is more about the principles and not the actual posture.<<<
Wonderful
My feelings exactly. It doesn’t matter what Bagua you learn, what forms you learn, what palm changes you do.
The movements and postures alone will never lend to the great internal potential with without tapping into the real power source first and that is found with in the principles and basics of what make an internal art, internal.
A posture is just a shape of an outlet for internal power, it really meaning nothing in the grand sense of the word “posture,” its what is underneath it, the power behind it that makes what Bagua postures are and what they are not.
All good Bagua is going to have “givens” which are techniques and or postures and methods of developing internal power, neigong, waigong and qigong that share in similarities because 1. it MIGHT have all came from the same place, 2. What one master/student/method did another enjoyed and found very effective and so they copied it, and 3. If it has existed this long it must have worked cause it’s teachers and students have fought and lived to bring it to us.
Bagua is the art of change, yeah I know we hear that a lot from certain people here and yet we never get a good explanation why…
The YiJing talks about Change as being the only constant we can expect from the world, both inside us, outside us, things we have control over and things that we do not. Change however doesn’t always mean one to the other and existing between to fringe extremes of the opposite or unknown.
Change is often more in the middle more mild and lends to the idea of changing and yet remaining the same, what Bagua offers is a way to adapt and change but keeping sense of our inner core and truths we know to be sound and tested, so that we are not lost to ourselves to the totality of the changing world around us.
This is played out in all the different style of Bagua. Bagua has an inner core and truths that make Bagua what it is, the art of Change is really more expressed in how so many different people use and express Bagua in different ways but will always have the inner core and truths to share and be martial brothers and sisters without prejudice to teacher, style or even postures 
Bagua is like that grandfather clock in a thunder storm, it will always keep a steady pace.