Yoga is the mindstuff whirling ceasing.

Part of the genius of Patanjali is that a simple format is followed throughout the sutras.  Make a statement, then refine the components of that statement. First we are told we will be instructed in yoga, then we are told what yoga is.

For Patanjali yoga is presented as the blissfully simple clarity of mind.

In this context clarity is stillness. Just as when the water of a lake is still we can clearly  see through it thus when the mind is still we have achieved the state of yoga.

The Patanjalian concept of mindstuff, “Citta”, comes from the root “Cit” which can be translated as ‘to think’ or ‘consider’ – note that this is an active process from which I infer some degree of practice may be necessary.

Citta is made up of three elements:

• Buddhi. The capacity to discern, to be awake.
• Ahamkara. The individuating principle, the sense of I in “who am I?”, the part which enables us to function as an active individual in the world. If the recipe of our personality in this lifetime is written by samsara, with our past karma as the ingredients, Ahamkara is the chef who puts it all together.
• Manas. To continue the above analogy Manas is the taster of the finished dish.  The interpreter of  information in the context of the sense of I.  It is also through Manas that the information about the world is gathered.

Together these three elements describe the inner life of the individual. They are intertwined and co-dependent.

For Patanjlai the mindstuff is separate from consciousness. The mindstuff can be flawed, fooled, muddied.  Yoga is how we correct the flaws, educate and clear the mind, and find our way to consciousness.

The flaws in perception are born from the constant movement (vrtti) of the mindstuff.

For most human animals our mind is in a continual state of flux (vrtti), our senses feeding information to Manas, Manas interpreting how that information is relevant to Ahamkara, Buddhi discerning the nature of that information and what we need to do about it.

and what is yoga?

Yoga is when that whirling (vrtti) ceases (nirodhah).