Continuous refinement
The long-term study of ashtanga yoga, like the long-term study of anything, is a process of continuous refinement. The longer we practice, the more knowledge we absorb about the system and, maybe, we start to gain some insight into the intentions behind it. When we reflect on the structure of the primary series, for example, we might start to question why we start with the standing postures, not the seated ones; why do the backbends only happen at the end; why do we have some really challenging postures in the middle and some more manageable ones further on?
As we gain an insight into the structure and, therefore, the essence of the ashtanga system we may start to reflect on whether we need to change the way we approach the practice on a daily basis. If we find that we're regularly experiencing niggles or injuries, it is incumbent upon us to investigate why that is happening. If we practice through pain for long enough it's pretty likely that we'll eventually stop practising altogether and so, although ashtanga yoga seems like a very strict system, we sometimes need to discover subtly different ways of doing things which will then allow us to continue to practice for our whole lifetime.
That's not to say we should modify all the postures so that they are all achievable from the beginning. It's my belief, barring underlying injuries or conditions which prevent it, that we should start off learning the precise system of vinyasas which constitute the 'traditional' ashtanga yoga practice. It's important that there is some struggle in the learning of the practice; it's in this struggle that we sow the seeds of the revelations that can come through practice.
It's a bit like cooking. When you're learning how to cook something new, you follow the recipe to the letter. And the first few times you make it you'll do it exactly the same way. If it's perfect and it suits all of your taste preferences you might keep making that exact same recipe for decades. Over time, though, you might alter the recipe to suit your own tastes and preferences, or you might need to alter it in to allow for some dietary changes (you've realised you're intolerant to gluten or dairy, or you substitute minced beef for puy lentils because you've stopped eating meat). After you've made the same dish a thousand times it will bear a resemblance to the original one, but it's unlikely to be exactly the same.
Maybe I'm stretching the metaphor a bit here but, if you were to pass on that recipe to somebody else, you might find yourself giving them the original recipe, without your modifications, so that they may start with a clean slate which allows them to alter it to their own preferences over time.
It's important to me that the integrity of the ashtanga yoga tradition is kept intact for future generations. If every student who learned the practice added some modifications and then taught their own students the modified version, ashtanga yoga as we know it would be unrecognisable in just a couple of generations.
So I do believe that, when we start off we need to 'follow the recipe' that comes with the practice. But, if we find that we are suffering because we're trying to strictly follow a strictly system, certain elements of which are causing us physical pain and suffering, due to our own unique attributes, history, genetics and injury profile, then it is important for us neither to continue bashing our head against that particular brick wall, nor to walk away and give up entirely, but to find a new way to approach a practice that has so much to teach us.
Let me be clear; I'm not talking about wholesale changes to the practice, leaving out important postures just because they're hard, or adding in tonnes of new postures but, over time, we might begin to bring our own flavour to the dish that is ashtanga yoga. And that is entirely rational and sensible.
The most important thing, from a personal point of view, is that we find a way to continue to enjoy the practice into our older years. If we can't do that then, no matter how dedicated or determined we are, we are likely to stop practising, and we will lose so much.
Enjoy your practice and go gently.