Yes, at first the physical aspect of yoga will be what we focus on. But even then: figuring out how long we can stay and if we should rest pull in several very important concepts: truthfulness about our body's capabilities, non-violence in not pushing beyond our current physical limitations.
What I am presenting here is drawn from my own practice over the past ten years and the teaching I've been blessed to do through the last six. Basically, it's just my take. Others here will have more to say, and I hope they'll share! There are a couple short articles that may give more ideas.
When we begin yoga we don't know what is going on in our body, much less our mental/emotional reactions to it. Take a seated forward bend - Pascimottanasana. At first, those toes may seem eons away and your back might be screaming at you for years of neglect. After a while though, you can rest more comfortably in the pose, but then you might begin looking at the people around you and notice how much further they are towards the floor with their faces. They might have been coming just as long as you - why are they further along? You might begin pulling/pushing/straining towards the floor, your toes. Conceivably, violence could arise in forcing the pose and berating yourself for not having 'got' it like the other students; you might slip into talk about how of course that person can fold like that: look at how skinny they are! if you were that skinny you could do it too - bringing a covetous/grasping mental idea of wanting their structure/body/size/abilities.
Or, say you used to be able to go down to the floor. Now, for whatever reason, you are hovered above it. Again, you might force and berate to get to where you used to be, but you are also exhibiting attachment - to the pose you did before, to the idea that there is a 'perfect' pose and you are not in it. And, again, you'd not be content with where you are in the here and now.
If you are put in a challenging standing pose, and the teacher keeps you for a good long time: are you practicing tapas/discipline by remaining? Are you really choosing the arm option, for instance, that is best for you today? Or is staying pushing you beyond what is appropriate for you at the moment? Struggling to bind your arms or do the final step/krama of the asana rather than stay at the preceding one which is best for your body? You can look at this as a matter of tapas and non-violence working with yourself physically, and internally you may have the ability to notice the way you respond to being asked to stay in the posture, as relates to the other principles. Many students begin to make evil eyes at the teacher when they overwork - they project the difficulty outwards, even when they've been told to release whenever they need. If we are working to create ease and peace in ourselves - how is that helping us?
If I am asked to stay in Utkatasana/Chair pose for an extended time the best place to look at how the ethics are working is inside: am I present with the reality of the pose (truthfulness) do I make adjustments and modifications that allow me to remain calm and centered in the pose (contentment) or do I begin to curse the teacher? curse my legs? do I start imagining my perfect body and tell myself that I'm not good as I am and this will help me attain that ideal? If those begin to come into play, I'm not practicing non-violence, I'm not practicing non-grasping and hands down, I bet you that when I'm in a difficult situation in my life: on the phone to my insurance, standing in line at the grocery store when I'm in a rush, in a disagreement with a friend or partner - those say tactics will come into play. What I say to myself on my mat shines a light on my inner dialogue and will point towards where I don't fully integrate these principles in my life.
Another example: if, as a teacher, I lead a class through a sequence I learned from one of my teachers, but I don't state that - can I say I'm practicing non-stealing? If someone comes up a after class and says they really loved it and my sequencing is awesome and I don't credit my teachers as having shared their routines with me? Is that really non-stealing in action? At the grocery store if I don't speak up and tell the clerk they've just rung my organic lemon up at .25 cents rather than the .99 it is priced - not practicing non-stealing.
If I'm using my class time to check out the other students and teacher, and I let my mind run fantasies about having relationships with them, and even if I act or don't act on them - it's likely time to start working with bramacharya and clarify what it means to be sexually appropriate. I find this to be a big one with the ever present issues around tantra and people asking 'does yoga help have better sex?' - it may be a perfectly legitimate question for some, but for many, it's just another distraction, the substitution of sex for a foundation upon which a relationship can be built.
So, yeah - ethics on the mat comes to our lives. Our lives are busy, full of colour and events. Our yoga mat is simpler. Group classes for many are a refuge from the hustle and bustle of life. And that is great because it offers a quiet place to, over time, begin noticing the underlying patterns and habits that we have and don't notice in our life away from the mat, and let's us start practicing in simplicity, what it's like to not give into the negative ways or being and acting. Our mat is a laboratory for these things to arise and be attended to.
At least, that's how I see it. And I've got some good feedback from many people in my life that it has made me a gentler person (people aren't scared to have me drive anymore!), a more honest person (I've gone back to more than one store to say they undercharged or didn't charge me for something) and so on.
While this isn't what you asked me to elaborate on, I found it interesting that the dictionary states the following:
representing a number of different Christian churches See note at universal .
• promoting or relating to unity among the world's Christian churches : ecumenical dialogue.
I'm a bit of a semantics sort of girl, since I was taught in philosophy classes that due to the high number of definitions words has we should always clarify and define the terms we want to be using, especially if it's not the common one. There was only this one definition though for ecumenical. Not cross faith dialogue, multiple Christian dialogue. Interesting, no?