This special truth(rtambhara) is totally different from knowledge gained by hearing, study of scripture or inference.
That knowledge is different from the knowledge that is commingled with testimony or through inference, because it relates directly to the specifics of the object, rather than to those words or other concepts.
When you achieve wisdom-filled-with-truth, you can understand everything, through your own experience, rather than through study. Through meditation, you can gain great wisdom into the nature of yourself and the universe.
This is rtambhara prajna, or the absolute true consciousness.
The experiential knowledge that is gained in that state is one of essential wisdom and is filled with truth.
After attaining concentration without subtle thoughts, there is ‘wisdom-filled-with-truth’, or rtambhara. Patanjali goes on to further describe this in the next sutra.
In the purity of nirvicara samadhi, the supreme Self shines.
As one gains proficiency in the undisturbed flow in nirvichara, a purity and luminosity of the inner instrument of mind is developed.
Nirvicara is meditation without subtle thoughts. Once one has mastered this, there is a higher level of serenity.
Each of the above kinds of samadhi are sabja (with seed), which could bring one back into bondage or mental disturbance.
These four varieties of engrossment are the only kinds of concentrations (samadhi) which are objective, and have a seed of an object.
These four samadhis or meditations on an object (with gross thoughts, without gross thoughts, with subtle thoughts and without subtle thoughts) still do not take us to the final goal. The seed of desire still remains, because the mind has not been totally purified.
The subtlety of possible objects of concentration ends only at the undefinable.
Having such subtle objects extends all the way up to unmanifest prakriti.
Prakriti means the most subtle matter that there is – Satchidananda describes it as:
the primordial basic substance in its unmanifested condition
Patanjali is saying here that the mind has the power to contemplate the most subtle matter that there is, from the gross through the subtle levels.
In the same way, both savicara (reflective) and nirvicara (super or non-reflective) samadhi, which are practiced upon subtle objects, are explained.
In the same way that these engrossments operate with gross objects in savitarka samapattih, the engrossment with subtle objects also operates, and is known as savichara and nirvichara samapattih.
This is the third of four types of engrossment with an object. All gross thoughts have been set aside, subtle thought patterns become the focus of meditation, streams of other subtle impressions accompanying them.
When the memory is well purified, the knowledge of the object of concentration shines alone, devoid of the distinction of name and quality. This is nirvitarka samadhi, or samadhi without deliberation.
When the memory or storehouse of modifications of mind is purified, then the mind appears to be devoid of its own nature and only the object on which it is contemplating appears to shine forward; this type of engrossment is known as nirvitarka samapattih.
Once the mind is devoid of qualities (such as attachment to the senses or physical objects), there is only the knowledge of the object being meditated upon,its essence, as well as knowledge of the Knower.