Samadhi is the term used to identify the highest state of self-identification. It can also be said as standing within one`s Self, Sameness; contemplation; union, wholeness; completion and accomplishment. In hatha yoga Pradipika, the term stands quite synonymous with Raja Yoga. Hatha yoga is not merely a physical form. On the contrary, Hatha is a distinct tradition that places a strong emphasis upon the integrity of physical, subtle-physical and mental discipline for the attainment of the very highest goal. Raja yoga corresponds to the kaivalya state in Yoga sutra. This is the ultimate goal of Hatha yoga and for that matter any type of Yoga.

The indicators of success in Hatha yoga are as follows:
Beauty and slimness of physique, radiant complexion, the "bursting forth" of the "inner sound", clear eyes, freedom from illness, control over subtle seminal fluid, intensification of the "inner fire", and purity of the Nadis. Such signs do not constitute the final goal of hatha, but are, rather, conditional aims of the discipline. They are useful as they assist in the attainment of samadhi or raja-yoga. They also indicate about the progress of the disciple towards his chosen path. Raja yoga as the final achievement is more fully discussed in the Hatha Yoga Pradipika`s fourth chapter. Following are the synonyms of Raja Yoga, which are meaningfully described in Hatha Yoga Pradipika:
Samadhi - union, integration;
Unmani - negation of the (cognitive) mind;
Manonmani - fixedness of mind;
Amaratva - immortality (`non-death-ness`);
Laya - absorption, dissolution;
Tattva - truth, realness;
Sunyasunya - void yet not void, voidless void;
Paramapada - supreme state;
Amanaska - beyond (cognitive) mind;
Advaita - non-duality;
Niralamba - without support (i.e. self-sufficient);
Niranjana - without stain, pure;
Jivanmukta - living liberation;
Sahaja - Easy or natural state;
Turya - fourth state, i.e. the state beyond wakefulness, dream sleep and deep sleep.

In brief, Raja yoga refers to the state-of-being characterised by perfect equilibrium, in which nothing is lacking. It is the union or identification, of Jivatman (self) and Paramatman (Supreme being); the dissolution of the distinction between cognitive mind and atman Self, just as salt dissolves into water. The confusion may arise with mentioning of terms like "unmani" (negation of cognitive mind), which apparently suggests that, in the highest state, the mind is somehow negated, confused or perplexed. This should be understood as non-identification with the superficial perception of the world. Ordinary perception of our being and our life with reference to the world is discarded. The viewpoint transcend to a much deeper reality.

The state involves a complete mergence of `knowing` and `being`. Reality, no longer divided into `self and `other`, is realised to be all One. The definition of Yoga from Patanjali`s yoga sutra comprises just four words:
"Yogas Chitta-Vritti-Nirodha."
These four words convey the central doctrine of yoga. Following the wide range of meanings of these four words, few of them are mentioned below:
"Yoga if the annihilation of the modifications of the mind. Yoga is the neutralization of the alternating waves in consciousness."
"Yoga is cessation of the turning of thoughts."

The mind or Chitta mentioned above can be regarded as a kind of short-hand for antahkarana the `inner cause` or `inner instrument` which comprises the three aspects of Buddhi (intelligence), Antahkarana (inner conscience) and Manas (mind). Buddhi is the most refined aspect of the three and is `responsible for the higher-level intellectual functions, which require intuition, insight and reflection. This is the aspect which in more implied in Patanjali`s definition. It is Buddhi that has the potential to `reflect` the pure light of Purusha. Manas (from the root man, `to think`) have two functions: One of which is to perceive the raw data obtained via the senses, and to turn into a usable picture of reality. Second functions of Buddhi is to take care of experiences composed of various arrangements of sense data in the form of `subliminal impressions (Samskaras) and memory traces.

Comprising these two functions of buddhi with the other two aspects, Chitta stands for the mind in its entirety. The emphasis is more dynamic than is afforded by the term "antahkarana". In the Indian context at least, mind is more a conglomeration of faculties and phenomena than a single entity. Vrittis refers to movement, momentum, habituation, and may also signify a `whirl`, `wave`, `ripple` or other distorting influence upon a pool of otherwise calm water. In yoga psychology, the term denotes distortions or modifications in the true and undistorted nature of Chitta.

The conclusion being that if Chitta is defined as `mind`, Chitta-vrittis are the `modifications of the mind`. These vrittis prevent the light of "Purusha" whose nature is held to be pure consciousness from being clearly reflected, and which therefore prevent us from identifying ourselves as the true Seer or Self. The Vrittis must be pacified before the Self can be realised in its fullness. This process involves a systematic transformation of Chitta. Many vrittis along with the tendencies to form new ones are so firmly ingrained within the mind, that only a rigorous regime of mind control and purification only can take those out of their roots. The process of yoga must be one involving deep penetration and the uprooting of habituated psychic modes. Any Vrittis (mental state or process) has the power of reinforcing itself each time it occurs, leaving behind `subliminal impressions` in the mind known as Samskaras. Samskaras are sublimal activators that provoke automatic or inhibited responses to situations.

Yoga psychology has it chitta or even budhi in itself is not responsible for the ultimate perception or experience. They are themselves part of the phenomenon of the world. There exist a difference between phenomena and reality. The one who perceives the ultimate truth is absolutely non-phenomenal. That is, it can never become an object of consciousness, in a sense is consciousness itself. This Perceiver, Seer or Self whose nature is consciousness is termed Purusha. It is Purusha that is held to `shine through`, `illuminate` and `be reflected in chitta.

Chitta may be regarded as a vehicle for consciousness. It provides a mechanism by which purusha can perceive and enjoy its own nature. This enjoyment has to be pure to realize it to the fullest possible extent. In other words, its pure and worthy components must be maximized. Characterising chitta as a mirror, we might say that all smudges and stains must be removed from its surface, so that the true reflection of Purusha can be seen. It is the `dissolution` of these distorting factors that constitutes nirodha.

Nirodha is defined as restraint, restriction or destruction. But according to yoga sutra, Nirodha is neither suppression nor restriction, nor even absence. Instead, yoga sutra renders Nirodha as `control` and in the second, as `dissolution`. Its an another thing for vrittis for `dissolving` or `merging` into chitta, and quite another for `rendering the vrittis non existent`. But in the later case, yoga has no scope. It achieves only the former goal. It is similarly impossible to destroy vrittis, as they are the part of mind. However, Many misinterpret assume Nirodha as a means to dull or "kill" the mind. Based on this assumption, the goal of yoga is viewed as an ontological severance between purusha (the source of consciousness) and prakrti (the source of phenomena, including citta) in which the mind is expunged. To avoid such ghastly error, Chitta Vritti Nirodhas can be instead viewed as the cessation of or misidentification with the modifications (vritti) of the mind (chitta). In other words, Nirodha can be described as the transformation of selfunderstanding, and not the cessation of Prakriti.

The yogi is no longer `attached to`, or `misidentified with` the mind and its modifications. It is therefore able to express him or her through means of those mental processes without being enslaved by them. The term Nirodha in the context of hatha-yoga, also relates to the effects of yoga practice upon the `vital force` or life principle known variously as prana, Vata or Vayu. This is not a huge detour as the relationship between chitta and prana is held to be extremely intimate. Any change in the condition of one affects a corresponding effect upon that of the other.

"When vata is disturbed, then chitta is disturbed. When vata is undisturbed, then chitta is undisturbed; thus the yogi attains steadiness (sthanatva) [by means of] vayum nirodhayet.

The phrase vayum nirodhayet Literally means nirodha of the Prana. It is inappropriate to translate nirodha as `dissolution`, for the yogi`s aim is to retain the vital principle within the body, not to dissolve it. Here Nirodha may be understood as a suspension (of flow) or the `harnessing` of prana.

Degrees of Samadhi
On the opening sutra of the Yoga-Sutra, Vyasa states that `yoga is samadhi`. This statement by itself draws attention to the utmost significance of samadhi within yoga praxis. As a matter of fact, the respective meanings of yoga and samadhi are very close.

The forms of Samadhi mentioned above are the schemas though not having mentioned in any direct Hatha Yoga Treatise or any near equivalent, is absent from those treatises most immediately connected with hatha-yoga, they are definitely mentioned in Yoga Sutra and Yoga Bhashya. The conclusion is that these schemas of samadhis are well-integrated framework of Foundation of Yoga itself. Hatha yoga is not merely a physical form. On the contrary, Hatha is a distinct tradition within the broader Field of Indian soteriology that places a strong emphasis upon the integrity of physical, subtle-physical and mental discipline for the attainment of the very highest goal.

Raja yoga corresponds to the kaivalya state in Yoga sutra. This is the ultimate goal of Hatha yoga, and for that matter any type of Yoga.