All experience takes place within duality. Duality is the mechanism of manifestation. Its fundamental poles are consciousness (cit), and energy (xakti) expressing as the fundamental operative principles of duality:Puruxa and Prakriti which manifest in cognition as subject (seer, knower) and object (seen, known).
The secret of duality is that its poles are neither separable nor in conflict. Rather they generate, define and fertilise each other: while at the same time containing and limiting each other. This containment is not a function of conflict but of fertility. When this secret is overlooked the mind lapses into the deluded state of dualism, wherein opposites are taken to be in conflict.
Subject (consciousness-of) and object (perception) polarise in action. This action is the dualistic (perceptual) field of perceived subject, object and the action(s) that link and define them. The terms that patanjali uses here are the grasper(grahitr), the grapsed(grahya) and the grasping (grahana). These terms refer to the activation of dualism or separation within the field of activity (duality). The grasper, or apparent subject is an expression in form, or manifestation, of the fundamental subject-principle: Puruxa. The grasped, or apparent object, is an expression in form, or manifestation, of the fundamental object-principle: Prakriti.
Elsewhere Patanjali uses synonymous terminology to refer to the expressions of these twin principles within the coarse and perceptible expressions of manifestation. These are the owner, owned and owning; seer, seen and seeing; knower, known and knowing. Other synonyms can be inferred such as doer, deed and doing. The fact that these terms are synonymous and therefore interchangable is indicated by the way Patanjali uses them. In ii.17-21 he uses the terms seer and seen while explaining their nature and origin. Then when summarising the nature of their relationship he switches to the terms owner and owned. All of these synonyms express and refer to the fundamental cognitive principles of subject and object, always linked by action (at the very least, perception).
This dualistic field is overtly a split but is inherently undivided and one, with its polarisations being functions of its appearance rather than its inherent, or even true, nature. The unified field is the singular matrix of consciousnessenergy. Localisation of the matrix in the human organism creates the appearance of a distinction between this and that localisation, and any aspect thereof: the illusion of separation, wherein apparent objects apparently impose apparent actions on each other. Separation or duality is the nature of the manifestation of consciousness in form, but nonseparation or nonduality is its inherent nature, which is neiter eradicated nor limited by its manifestation.
When vrtti are no longer identified with they begin to (apparently) slow down. The mind starts to quieten within its internalisation. Eventually pockets of total quietness or stillness spontaneously emerge. Within these pockets consciousness shines within its localisation uncolured by any attribute, quality or condition. Within this unconditional state the fundamental dualistic conditions of subjectness, objectness and action no longer assert themselves. They interpenetrate (samapatti) each other and dissolve in their union (yoga).
Interpenetration, or the merging of subject and object, has four aspects, each of which elicits insight into the nature of perception, cognition and phenomenalisation. These insights then ripen as functioning imprints in consciousness. These imprints, in turn, generate a disposition that takes account of the impersonal heart of all phenomena: a disposition from within which no action or object is identified with anything.
Vitarka samapatti results from complete penetration of (intimacy with) the conceptualised characteristics (inflamed, bulbous,) that constitute perceived objects (nose). It provides insight into their conditioned, representational and projected nature. Conceptualised characteristics are no longer taken to have independent existence outside the perceiving mechanism. This weakens the tendency to objectify and identify that causes so much misunderstanding, confusion, enmity and strife.
Nirvitarka samapatti results from complete penetration of (intimacy with) the sum of perceived characteristics of an object as the object itself. This includes not only its form, but its implications and context also. It provides insight into the conditioned, representational and projected nature of individual objects. Perceived objects are no longer taken to have independent existence outside the perceiving mechanism. This weakens further the tendency to objectify and identify.
Vicara samapatti results from complete penetration of (intimacy with) perceived qualities (red, curved, straight) underlying perceived characteristics and objects. It provides insight into their conditioned, representational and projected nature. Fundamental perceptible qualities are no longer taken to have independent existence outside the perceiving mechanism. This weakens further still the tendency to objectify and identify.
Nirvicara samapatti results from complete penetration of (intimacy with) the dynamics of perception itself, and objectness itself is seen through. It provides deep insight into the conditioned, representational and projected nature of subjectness, objectness, phenomenalisation and perception: thereby elucidating the nature of the (projective) perceptual mechanism. Perception and cognition are no longer taken to be anything other than processes of limited functional representation. Their objects are no longer taken to be anything other than appearances in consciousness.
Interpenetration in these four aspects is the deepest possible cognitive intimacy. It arises only as a result of relaxing into that which is apparently happening. This relaxing into is rupanugamat which literally means to connect with the form, and indicates a profound penetration of object by mind. Rupanugamat is the key process of yoga. It is the process whereby the split between the perceiving subject (the seer, doer, owner or grasper) and the perceived object (seen, deed, owned, grasped) resolves. The resolution of this split is not a function of effort. It is the effort of intent, however subtle or subliminal, that causes the split. It resolves in the letting go of effort. Rupanugamat is what happens when the relaxation of the mind occurs through total, effortless absorbtion into an apparent object. Mind and object become one. The penetration of rupanugamat is mutual between subject and object and results in the resolution of their apparent difference in interpenetration (samapatti), whereby their inherent nondual nature is elucidated (paridrsto).The "most subtle depths" (i.45) of any apparent object, according to Patanjali, is the fundamental ground of manifestation (alinga), which is formless consciousnessenergy (citixakti) itself. In other words the inherent movement of consciousness itself as pure, undifferentiated energy. It is by elucidation of this shared essence and source that differences between apparent objects (including the operative subject) are revealed as being apparent productions (projections) of a limited perceptual perspective.
A perspective, however, that is functionally necessary. In other words phenomena are not in themselves as they appear to be. They are repreentations in awareness whose particular characteristics and qualities derive substantially from the nature of the perceptual mechanism wherein they take their existence. (The falling of a tree creates only vibrations (xakti), which only become sound when the appropriate mechansim is at hand. Sound is generated in the brain , as a result of the interaction of vibration and a sensory nervous system.)