I have been practising yoga since 1972 -- back then I started classes with BKS Iyengar in the UK. I count myself very lucky to have been taught by him then because Iyengar was a relatively unknown yoga teacher, which meant the classes were small and relatively personal.
One of the most important aspects of yoga, which I have learnt over these years, and I put aside a certain amount of time to practice yoga every day, is that stiffness is an essential part of what yoga is. Even at its essence, the physical and neurological limits we reach when practising a posture/asana, is like a barometer from which we can measure how and how not to work a posture/asana.
In my experience, how we do yoga is more important than whether we can bend backwards, or reach our toes in a forward bend for example. Whether one is, or is not flexible is not yoga -- If we are constantly competing with other people, or measuring ourselves against ourselves, to see how far we can stretch in a posture/asana, then this is more akin to a competitive sport than it is to yoga.
The word 'yoga' is derived from the Sanskrit root 'yuj', which means Union -- the union of the body, mind, emotions and intellect.
Certainly with practice you will see many physical benefits and perhaps eventually touch your toes, or even get into the lotus position; but this doesn't mean that when you reach your flexible goal, you are at one with the physical and psychological body, the universe, or indeed the great sea of consciousness.
Yoga helps us to see, feel and realise the physical, material plane, joining with the spiritual -- in this true sense it is the union of the individual self with the universal self.
When working a posture/asana, the body and mind are opening up a dialogue. The combination of muscular movement and nervous system relays signals to the brain, telling us exactly how and where we are in our body and where the body is in space. This interchange is the beginning of two separate states uniting to become one. This physiological and psychological coming together, sees the cessation of the chattering mind and unveils the true beginning and foundation of yoga.
It could be seen that when we are walking towards our destination our back leg is in the past and the front leg in the future, with the torso and the head, in the present; but you could see walking another way! you could say that we are not leaving the past and going towards the future, but merely moving through the present from one place to another and then we could take this a little further by seeing everything in the past and future as in the present -- anything that has seemingly past away has merely changed or evolved into another form of matter.
In yoga the idea is to join all the dimensions of the body together, thus becoming one with the present, it is then that the beauty of what is now, who we really are, can be taken in. This isn't difficult, but at the same time it involves looking deeply into who and what we are. This is not analysing, but more to do with observing; observing without judgment as to how we are, how our breathing is, how the muscle contracts and expands along with the nervous system.
By observing, working with the body, fully, with alertness, awareness, we learn how to release the tension and bring life, where there might otherwise be a mind-set that is conditioned into closing us down.
With continued practice, as well as becoming subtler, the relationship between the body and our awareness becomes increasingly animated and in so doing has the capacity to find its true place in the all-singing, all-encompassing unfathomable now. To refine this song of songs still further, means the tautness is essential, just as the strings of the violin bow can only play the right note if the strings are just so, neither to tight nor too lose.