tadā draṣṭuḥ svarūpe'vasthānam - YS 1.3
YS 1.2 yogaś citta-vṛtti-nirodhaḥ - is always heralded as the definition of yoga as per Patanjali, but this sutra is pretty meaningless without its follow up sutra 1.3.
While 1.2 tells us that yoga is concentration/stilling the mind/absorption etc - 1.3 tells us what happens when concentration takes place.
1.2 tells us about technique but 1.3 tells us about the result and therefore also the purpose of yoga practice.
Like the famous buddhist parable about the finger pointing at the moon - the finger is not the intended target of attention, the moon is - sutra 1.3 tells us about the actual target of yoga practice.
Which is... once the mind has been stilled, then the draṣṭuḥ - the Seer - is established in its own (sva) form (rūpa).
In other words, when the mind stops moving we experience consciousness, our true essence, as it is. In the next sutra Patanjali explains - 1.4 vṛtti-sārūpyam itaratra - at other times consciousness follows the form of thought/experience.
The word sutra means thread. The sutras are woven together to make a fabric of interconnected ideas. These three sutras belong together and only become meaningful when considered in concert.
It was stated above that in the state of samadhi, the Seer is established in its own form - this is a bit misleading. The nature of consciousness is that it has no form. A better translation might be the Seer is established in its own state, or its natural condition, its unconditioned state, its pure essence.
According to yoga, embodied existence is a dual condition. Consciousness is not a material thing, while mind and body are both material in nature.
Mind is an element of prakṛiti - material nature. Mind is dependent on the brain, nervous system, endocrine system, internal organs etc. as well as sense data, material facts, concrete memories, emotionally distorted memories, instinctive drives etc..
These elements that are material in nature are the forms that consciousness fills. Consciousness is itself formless but like water it fills any container, it forms itself according to the boundaries created by the container - whether they be thoughts, memories, emotions, perceptions, passions etc.. The mind creates the form and consciousness fills the form.
That is why one can only become aware of the true nature of consciousness, when it is not colored by, delimited by or formed after the contours or currents of the mind. Only when the mind is empty and still can consciousness be experienced as it is.
The nature of consciousness is reality, consciousness and bliss - Sat-cit-ānanda
This is our true, essential nature. A healthy human being will naturally experience times of tranquility when the mind ceases activity and feels identification with essence. However in our modern era, with all its stresses and our unhealthy lifestyles, this phenomenon rarely takes place.
Since consciousness seems to take the form of thoughts and mental activity never ceases, we have lost sense of who or what we truly are. Our best bet follows the course of our mental patterns. We identify with our habits, professions, sexual orientation, political affiliation etc.. but we feel somehow lost, disconnected from our real being, our true identity.
This is why we need samādhi. Samādhi brings us back to health by allowing us to remember who and what we truly are. Am I this body? Am I this mind? These elements that are going through continuous change? Or am I something that has permanence and depth? Am I something that transcends the day to day, that transcends suffering, small mindedness, ignorance etc.? I think we feel this instinctively even though today we are told we are nothing but biology.
"The hard problem" and the simple solution.
Western psychology assumes that consciousness is predicated on biology. What is known as "the hard problem" in psychology is to trace the link between neural activity and consciousness. This link has not been seen or adequately explained.
Even though modern science assumes that consciousness is "caused" by material processes, the irony is that all material processes can only be known indirectly, whereas consciousness is the one thing that can be experienced immediately.
All observations about the world are mediated through the mind and senses and presented to inner consciousness. We cannot directly touch, smell, see anything material - every experience is mediated via the senses (which may function well or not).
The only thing that we can be concretely and objectively aware of is consciousness itself - so the only true science we can do is to observe our inner being.
Although the inner Self is the only thing we can truly know concretely, ironically, the science of self, or psychology, is the least developed scientific field.
Western psychologists have resisted looking at consciousness directly and only look at the consequences of conscious activity (behavior), while in the East, consciousness has been a central focus of observation for thousands of years.
The problem is that you cannot directly observe another person's consciousness. One can only observe the effects of consciousness - ie behavior/images recorded by fMRI machines etc.. There is only one place one can look to observe consciousness directly - within one's own experience.
A science of subjectivity! Is this an oxymoron, or is this the only true science possible?
Since all experience is mediated via the subjective apparatus of mind and senses, how can knowledge be truly scientific and objective? Before looking at facts of the world, we had better improve the instrument of knowledge. Then, maybe, our conclusions will become valid.
But since the mind is dysfunctional, impure, imprecise, incapable of being controlled - and is the preeminent scientific instrument - should its mastery (yoga) not be the first scientific discipline?
Understanding consciousness is not "the hard problem" because we cannot get our heads around it. It is the hard problem because we cannot control the mind and stop thinking!
When the mind stops thinking, consciousness abides in itself.
The simple solution.
According to yoga, consciousness does not depend on biology - consciousness is non-material in nature. This could only be known through direct experience when all activities of the mind body have been suppressed.