3.The eight limbs of यग [yoga]

“The eight components of yoga are external discipline,
internal discipline, posture, breath regulation,
concentration, meditative absorption, and integration.”
Patanjali, CH-II, The Yoga Sutra

In the yoga sutras, Patañjali has systematized the discipline of यग [yoga] into eight limbs leading to the supreme state of समतध [samādhi] :

यम	नियम	असन	प्राणयम	प्रत्याहार	धारण	ध्यान	समाधि
yama	niyama	asana	prāṇāyāma	pratyāhāra	dhāraṇa	dhyāna	samādhi
Moral commandments	Moral discipline	Postures	Breath control	Withdrawal  of senses	Concentration	Meditation	Super-conscious state

3.1. यम - [yama]

“The five external disciplines are not harming, truthfulness,
not stealing, celibacy, and not being acquisitive.”
Patanjali, CH-II, The Yoga Sutra

यम [yama] (universal moral commandments) and तनयम [niyama] (self purification by discipline) are the two first stages. They state the ‘does’ and ‘don'ts’ to be followed by the यतगन  [yogin] in order to lead a healthy and peaceful social life. They also help the यतगन  [yogin] to control his passions and desires and thereby, condition his body and mind to the next stages.
यम [yama] is the name of the first man who became at his death, the god of the death itself.
In the yoga sutras, this term refers to the ethical commandments stated below :

अहिंसा	सत्य	अस्तेय	ब्रह्मचर्य	अपरिग्रह
ahiṃsā	satya	asteya	brahmacharya	aparigraha
Non-violence	Truth	Non-stealing	Chastity	Non-coveting

3.1.1. अहस - [ahiṃsā]

अहस [ahiṃsā], the principle of non-violence is the first and most famous यम [yama]. The letter अ [a] in sanskrit stands for the negation of हस [himsa], which means violence. अह स [ahi ṃsā] is based on love and the sentiment of unity. The यतगन [yogin] considers that every single creature has as much right to live as he has and that the act of killing is an offense to the creator. That is why many Hindu respect a vegetarian diet. The यतगन [yogin] also believes that violence arises out of fear, weakness and ignorance and that the best way to fight it is thereby follow the path of knowledge. The Mahatma Gandhi is certainly the greatest incarnation of this principle which is omnipresent in the indian tradition.

3.1.2. सतय - [satya]

सतय [satya] is the principle of truthfullness in the speech, the action and the way to behave. Mahatma Gandhi said “Truth is God and God is Truth”. It is also considered that the one established in truth, stands closer to god and will be given what he really needs and prayed for.

3.1.3. असय - [asteya]

असय [asteya] basically stands for non-stealing. In a larger sense, असय [asteya] means respect of property and honesty. This principle preserves the यतगन [yogin] from anger and violence while trying to steal other’s goods.

3.1.4. बहय

[brahmacharya]

बहय [brahmacharya] is probably one of the most controversial and misinterpreted यम [yama] in both the West and India. Contrary to most of the ideas received it does not order to observe chastity and remain bachelor all the life along. बहन [brahman] is the name of the supreme God which lies inside every mind and object. Thereby, the one who sees divinity in all can be considered as a brahmachari.

बहय [bahmacharya] as realization of god becomes possible only through the practice of self-restraint, which means restraint of all the senses. The control of sexual instinct is particularly important to attain बहय [bahmacharya]. The यतगन [yogin] shall thereby not restrain his sexual activity but he has to keep a complete control on it and moderate it as the sexual energy can be source of sin. बहय [bahmacharya] can thereby be regarded as a source of energy to accomplish the work of the lord and follow the path of knowledge.

3.1.5. अपररग - [aparigraha]

अपररग [aparigraha] is the wish of poverty and the dettachment from material goods and money on which it lies. The यतगन [yogin] has to overcome the desires to possess and fascination for objects, which are known to be sources of sorrows, frustrations and pain. This principle is deeply anchored in the Indian tradition too. It is for example common to cross the path of some aspirants known as saddhus who have renunced to all material things.

3.2. तनयम - [niyama]

“The 5 internal disciplines are bodily purification, contentment, intensity, self-study, and orientation toward the ideal of pure awareness.”
Patanjali, CH-II, The Yoga Sutra

तनयम [niyama] which literally means restriction, is the second stage of rajayoga dealing with moral discipline. The five तनयम [niyama] are the following :

शौच	संतोष	तपस्	स्वाध्याय	ईश्वर प्रणिधान
śaucha	saṃtoṣa	tapas	svādhyāya	īśvara praṇidhāna
Purity	Contentment	Austerity	Study of the self	Devotion to god

3.2.1. श - [śaucha]

शच - [śaucha] is the principle of purity without which the withdrawal of senses necessary to meditate is impossible.
Physical purity of the body is necessary to remain away from sickness. While hygiena and good habits clean the body externally, पणयम [prānāyāma] ṇ and आसन [āsana] clean it internally.
A proper, healthy, soothy and juicy diet is also important to keep a healthy body and condition it for meditation. It is believed that food directly affects the mind and that eating sattvastik food will help the mind to remain still and peaceful. On the contrary, meat, coffee, tobacco, alcohol, sour, bitter and unhealthy food are considered as tamastik and have thereby to be avoided before meditation.
An aspirant following the path of yoga will sooner or late have to adopt a vegetarian diet.
Intellectual purity is even more important than physical purity. The cleansing of the चचत [citta : the mind] of its disturbing emotions such as hatred, anger, lust or passion. The cleansing of the बद [buddhi : the intellect] of its impure thoughts through भद [bhakti : devotion] or [svadhyaya : study of the self] procures happiness and peacefulness.

3.2.2. सष - [saṃtoṣa]

सष [saṃtoṣa] is often described as the state in which the flame of the spirit remains still
and undisturbed by the wind of desire. The Indian philosophy states that happiness is inversionally proportional to the quantity of material goods we possess. It is thereby not how much we have, but how much we enjoy it that makes happiness. But no happiness is superior to the one we get while sharing our food and goods with the ones in need instead of enjoying it alone. सष [saṃtoṣa] is much deeper than contentment as it also teaches to enjoy only what we need in order to distribute and share the excess with others. In a world where the ressources are wasted and unequally enjoyed, this principle is gold.

3.2.3. पस [tapas]

पस [tapas] derives from the root “tap” which means to suffer pain, consumed by heat. पस [tapas] is the burning effort involving self-discipline and austerity in order to attain purification of mind and attain unity with ईशर [īśvara]. पस [tapas] is related to three levels : the body, the speech and the mind. In everyday life, it implies the suppression of desires, avoiding harmful words and banning envy, jealousy, aggressivity and selfishness from our mind. It also consists in acting and working without selfish intentions and hope of reward, as stated in the bhagavadgītā.

3.2.4. सवधयय [svādhyāya]

सवधयय [svādhyāya] is the education of the self by the self. By सवधयय [svādhyāya], the यतगन [yogin] understands the nature of his soul and gains communion with the divine. Thereby यग [yoga] shall not be regarded as a religion, but as the science of religions ; the way along which the यतगन [yogin] will learn how to unify with the supreme and reach the state of vibration and peacefulness.

3.2.5. ईशरपणणधन

[īśvara praṇidhāna]

ईशरपणणधन [īśvara praṇidhāna] is the dedication of thoughts and actions to the supreme.
It does not necessarily mean to prey on the divine. It is actually more, being thankful and merciful toward nature and what each one conceives or not as the energy animating nature. Before devoting the self to the divine, the यतगन [yogin] has to free a place in his mind from sorrows and desires.
Then, he only can attain the state of त [bhakti], which is true love and dedication to the divine.
Work and actions reflect a better image of the self than words. By following the path of तयग [bhaktiyoga], the यतगन [yogin] mirrors and approaches the divine lying in him.

3.3. असन - [asana]

असन [asana is the third limb in the path of यग [yoga]. The असन [asana] are a succession of postures practiced while inhaling, exhaling or retaining the breath. They do neither aim at losing weight nor building the body but at making the body a fit vehicle for the spirit. By focusing the mind on breath and movements, they prepare for concentration. Meditating in the posture of the lotus can only be successful if the body and the mind are free from pain and sickness. By ensuring a good health and a supple body, the असन [asana] prepare the body and the mind for meditation.
There are thousands of different असन [asana]. All these harmonious postures have been practiced for several centuries before पञजतA [Patañjali] systematised them in the yoga sutra.
The name of the असन [asana] refer to concrete elements and illustrate the principle of evolution : पद [padma : lotus], मतसय [matsya : fish], वणक [vṛścika : scorpion], जग [bhuja ṃga : snake], नक [nakra: crocodile], तस [siṃha : lion]. Some असन [asana] also carry the name of divinities and legendary heroes like नम [hanuman], the monkey god, son of the wind.

असन [asana] should be practiced in the early morning or late evening in a clean airy place free from insects. As far as I am concerned, I prefer to practice in the evening as the body is less stiff than in the morning. What is more, concentrating on the postures helps me to release the stress and strain of the day. असन [asana] shall not be practiced directly on a rigid floor but on a carpet, blanket or tatami instead. Whatever the hour, असन [asana] should be practiced with an empty stomach, so that it is better to wait four hours after a heavy meal before starting to practice.
In all the असन [asana], the breathing should be done through the nostrils and not through the
mouth.

· [Tadasana]

Tada means mountain. Tadasana is the basic standing pose in which the body stands straight, the arms along the body. This is the starting posture of several postures such as the famous सयनमसकर [sūryanamaskar].

· पदसन [padmāsana]

पद [padma] means lotus. In this posture, the legs are completely crossed – just as तशव [śiva] in the picture – and the back has to be kept completely straight in order to allow a full flow of vital energy along the spinal cord. पदसन [padmāsana] is the posture used for meditation.

· सयनमसकर [sūryanamaskar]

The Sun Salutation सयनमसकर [sūryanamaskar] is a succession of 12 different and harmonious postures giving various positions to the spinal column. The Sun Salutation is a warm-up exercise that should be practiced before starting with the others असन [asana]. Following the tradition, the Sun Salutation cycle shall be repeated twelve times in the direction of the sun while repeating mentally the twelve names of सयन [Surya], the god of the sun.

3.4. पणयम - [prāṇāyāma]

"पणयम [prāṇāyāma] is the link between the mental and
the physical disciplines. While the action is physical,
the effect is to make the mind calm, lucid and steady.”
Swami Vishnu-Devananda

पणयम [prāṇāyāma] is the fourth discipline in अषङगयग [aṣṭāṅgayoga]. The पण [prā ṇā] are the vital breaths and अयम [āyāma] means lenght, extension, restraint. पणयम [prāṇāyāma] is the science of breath aiming at extending and controlling all its functions. The three fundamental states in पणयम [prā ṇāyāma] are :

पूरक	सत्य	कुम्भक
puraka	rechaka	kumbhaka
Inhalation	Exhalation	Retention

कमक [kumbhaka] can be either the interval between a full inhalation and exhalation or the interval between a full exhalation and inhalation :

सत्य कुम्भक	अस्तेय कुम्भक
Antara kumbhaka	Bāhya kumbhaka
Retention after inhalation	Retention after exhalation

Professor Shekar, who taught me यग [yoga] during several months in Chennai (Tamil Nadu, India), explained that the यचगन [yogin] believes that the life span is measured by the number of breaths remaining and that life duration can thereby be increased by practicing पणयम [prāṇāyāma].
Whatever the amount of truth in this principle, the practice of पणयम [prāṇāyāma] is essential to follow the goal of अषङगयग [aṣāgayoga] ṭ ṅ, which can be summarized asचचतवgदतचनरaध [citta-v tti-nirodha].
चचत [citta: the mind] is like a chariot attached to two powerful horses : one पण [prāṇā] and the other one is वसन [vasana : desire]. चचत [citta : the mind] moves in the direction of the most powerful horse. If desire dominates, breath is disturbed and the mind becomes agitated and the desires uncontrolled. On the contrary if breath prevails, the senses are under control and the mind is stilled. The control of the senses enables the यचगन [yogin] to reach the stages of पतयहर [pratyāhāra] and धयन [dhyāna] leading to the ultimate and mindlessness state called समचध [samādhi].
पणयम [prāṇāyāma] shall not be practiced without the guidance of a गर [guru].
पणयम [prāṇāyāma] should be practiced in a clean, quiet and airy place. The best periods to practice in Europe are spring and autumn for their temperate temperatures. Though some यग [yoga] schools consist in practicing असन [asana] in an artificially warmed atmosphere the original अषङगयग [a ā gayoga] ṣṭṅ should be practiced early in the morning or in the late evening in order to avoid excessive temperatures and perspiration in summer. पणयम [prāṇāyāma] shall be practiced before the असन [asana] with a lapse of a few minutes in Savasana in between. According to the Hatha Yoga Pradipika, the यचगन [yogin] shall practice 80 cycles four times a day. As it is hardly conceivable in our modern societies, a good practice could be to start with 15 minutes every morning.
The best postures to practice properly पणयम [prāṇāyāma] is पदसन [padmāsana : lotus posture]. Whatever the posture chosen, the back, the neck and the head should be completely straight in order to allow the vital पण [prāṇā] to flow deep inside the body. The body shall be completely relaxed and the posture comfortable so that no pain disturbs the mind. A good practice of the असन [asana] will not only prepare for concentration but also condition the body to sustain these postures.

· मद [mudrā]           

ज्ञानमुद्रा [jnana mudrā]	विष्णुमुद्रा [viṣṇu mudrā]

During the practice, breathing is done through the nose only and the eyes are kept shut in order to prevent the mind from wandering. The left hand lies on the left knee in the जनमद [jnana mudrā] posture while the right hand lies on the nose in the तवषणमद [viṣṇu mudrā] posture in order to control the flow through the left and the right nostrils. In some पणयम [prāṇāyāma] exercises, both hands lie in मदजन [jnana mudrā] on the knees. There are hundreds of breathing exercises, the following are the first I learned in India :

· कपAHत [kapālabhātī]

कपAHत [kapālabhātī] is one of the cleansing exercises known as Shad Kriyas. In Sanskrit, कप [kapala] means skull and त [bhātī] means shining. The origin of this appelation is that Kapalabhati is considered to be so cleansing to the entire system that, when practiced daily, the body shines with inner health and peace.कपत [kapālabhātī] is practiced seatted in पदसन [padmāsana : lotus posture] with both hands lying on the knees in जनमद [jnana mudrā].
A cycle consists in exhaling quickly through the nose while contracting violently the abdomen and inhaling passively while expanding back through the abdomen. When कपत [kapālabhātī] is done properly, the inhalation time is 4 times longer than the exhalation time. At the Sivananda Yoga Vedanta Centre, we used to start with two rounds of 30 cycles, but it can easily be increased to several rounds of a hundred cycles for instance.
The physical benefits of कपत [kapālabhātī] are multiple and I especially enjoyed expulsion of stress and tension, refreshment of the mind. Those are the main short-term benefits but the कपत [kapālabhātī] also cleans the breathing apparel, strengthens the abdominal and lung muscles and increases the breathing capacity. By increasing the capacity to breathe steadily and forcefully, कपत [kapālabhātī] conditions the body and the mind for concentration and meditation.
यतगन [yogin] exposed to asthma troubles shall not attend कपत [kapālabhātī] without the guidance of a guru. The beginners might experience perspiration and trembling. They disappear with time and practice.

· Anuloma Viloma (Alternate nostril breathing)

Sitting legs crossed, the left hand in जनमद [jnana mudrā] on the left knee and the right hand on the nose in तवषण मद [viṣṇu mudrā]. A cycle consists in :

N°	Left Nostril	Right Nostril	Time
1	Inhale completely	Closed	4”
2	Closed	Closed	16”
3	Closed	Exhale completely	8”
4	Closed	Inhale completely	4”
5	Closed	Closed	16”
6	Exhale completely	Closed	8”

Anuloma Viloma helps to calm the mind and prepares it for meditation. This exercise provides a peaceful sensation of a lighter body and mind. It is believed that alternating breathing through left and right nostrils purifies the balance of the nadis (psychic meridians).

3.5. पतयर - [pratyāhāra]

“When consciousness interiorizes by uncoupling from external objects, the senses do likewise; this is called withdrawal of the senses.”
Patanjali, CH-II, The Yoga Sutra

पतयर [pratyāhāra] is the fifth discipline in यग [yoga], consisiting in withdrawing from perceptions and senses. According to Indian philosophy, the source of sorrows and pains on earth are the pleasures and desires caused by a wrong knowledge of the true nature of objects. People tend to believe that eating an ice-cream, watching a movie or smoking a cigarette provides them with happiness and peace of mind but they are wrong. It is the fact that the movie focusses all our senses and mind on the pictures and sounds that provides a sensation of happiness, not the movie itself. Once the movie stops, the external disturbance of the senses and sorrows settle back in the mind. That is why our mind believes that happiness depends on objects and feels desires and sorrows if it is not going to get them. By managing to control and withdraw from its senses, the यतगन [yogin] suppress the source of all its sorrows and frustrations. He remains undisturbed by all the artificial pleasures and desires created by the objects of the modern societies and his mind lies in peace. That is why पतयर [pratyāhāra] is an essential step toward समतध [samādhi].

3.6. धरण [dhāraṇa] : concentration

“Concentration locks consciousness on a single area.”
Patanjali, CH-II, The Yoga Sutra

धरण [dhāraṇa] is well illustrated by Arjuna, the mighty bowman of the मर [mahābhārata]. Once Drona, the preceptor of the royal princes, organised an archery contest to test their proficiency. They were asked one after the other to describe the target, which was pointed out to them. This target was a nesting bird. But the princes described wrong targets such as trees instead. When Arjuna’s turn came, he described at first the whole bird, then he concentrated on its head so that he could see nothing but the shining eye of the bird which was the exact target chosen by Drona.

3.7. धयन - [dhyāna] : meditation

धयन [dhyāna] is the state that arises when the flow of concentration is continuous. As water takes the shape of its container, the mind when it contemplates an object is transformed into the shape of that object. The mind which thinks of the all-pervading divinity which it worships is ultimately through meditation, transformed into the likeness of that divinity. Once ततवतततनरध [citta-vṛtti-nirodha] is reached, the mind is freed from disturbance and become still just as the surface of a lake in the absence of wind.

“One can become fully absorbed in any object,
whether vast or infinitesimal.”
Patanjali, CH-I, The Yoga Sutra

· Japa Meditation

“Every Mantra has got tremendous force. A Mantra is a mass of Tejas or radiant energy. It transforms the mental substance by producing a particular thought movement.”
- Swami Sivananda -

Japa meditation is based on the repetition of a Mantra in order to reach ततवतततनरध [citta-vṛtti nirodha].
Mantras used by spiritual aspirants to achieve God realization are called Deity Mantras.
According to Meditation and Mantras by Swami Vishnu Devananda, every Deity Mantra possesses the following characteristics :

1. It was originally revealed to a sage, who achieved self-realization through it and passed it down to others
2. It has a presiding deity
3. It has a specific meter
4. It possesses a bija or seed, investing it with a special power which is essence of the Mantra
5. It also has a dynamic divine power, or shakti
6. Lastly, there is a plug that conceals the pure consciousness hidden in the Mantra. As soon
as the plug is removed by constant prolonged meditation, pure consciousness is revealed
and the devotee receives the vision of his deity.

· Hatha Yoga Meditation – Kundalini

कण [Kundalini] is the cosmic power in individual bodies. कण [Kundalini] is the goddess of speech and is praised by all. When awakened by the यतगन [yogin], she achieves the illumination for him. Also called Saraswati, she gives knowledge and liberation. She is Prana Shakti, the supreme force by which the world exists.
कणrAयग [Kundalini yoga] is the ultimate meditative state is the ठयग [haṭha yoga].
Arousing the Kundalini Shakti requires a good knowledge of the physical and psychic bodies and cannot be achieved without the guidance of a गर [guru].
In कण [Kundalini] meditation, the divine power that lies dormant in every human being is aroused and pulled upward through the क [cakra : energic centres], the psychic centres of the body. At the top of the head, the union of the individual and absolute consciousness symbolized as the union of कण [Kundalini] with तशव [śiva], takes place.
ठयग [haṭha yoga] awakens the कण [Kundalini] by disciplining the body, controlling the पण [prāṇa] and purifying the nadis, which are astral channels through which the पण [prā ṇa] flows .

· The Physical & the Cosmic bodies

कण [Kundalini] and her channels for movements are not to be found is the physical anatomy we study in the West. In the yogic theories, every portion of the physical body is given a counterpart in the astral body which is independant on the material plane. The astral body is thereby made of seven क [cakra] and approximately 72’000 nadis which are astral nerve tubes. The most important nadi is sushumna nadi, the counterpart of the spinal cord which extends from the muladhara क [cakra] to the brahmarandhra in the crown of the head. Along each side of sushumna nadi are two nadis known as ida and pingala and which correspond to the left and right sympathetic ganglia in the physical body.

· क [cakra : energic centres]

क [cakra] are energy centres of consciousness and awareness along the spinal cord. The location of the seven क [cakra] and their corresponding location in the physical body are the following :

No	Chakras	Plexus	Location
7	Sahasrara	Pineal gland	Crown of the Head
6	Ajna	Cavernous plexus	Between the eyebrows : trikuta
5	Vishuddha	Laryngeal plexus	Throat region
4	Anahata	Cardiac plexus	Heart region
3	Manipura	Solar plexus	Navel region
2	Swadhisthana	Prostatic plexus	Region of the genital organs
1	Muladhara	Sacral plexus	Lower end of the spinal column

During meditation, each क [cakra] is visualized as a lotus with a certain number of petals and a specific color, power, bija (mystic vibration) and deity. Each petal is associated with one of the 50 sanskrit letters representing the vibration produced as the कण [Kundalini] flows through
this.

· Practice of meditation

The best moments to meditate are considered to be dawn and dusk. Whatever the moment, it is essential to choose an hour at which the mind is free from the stress of daily tasks, work and worries. That is why it is more convenient to meditate is a calm and separate room.

“The postures of meditation should embody steadiness and ease.”
Patanjali, CH-II, The Yoga Sutra

The posture used for meditation is पदसन [padmāsana : lotus posture]. As this posture is difficult for westerners, it might be better simply to sit legs crossed on a pillow. As for the previous stages, the posture has to be comfortable so that no strain nor pain will disturb the mind while meditating. We now understand all the importance of a regular practice of the असन [asana], which helps to keep a supple body. Before beginning meditation, it is important to start with 5 to 10 minutes of deep abdominal breathing in order to calm and disconnect the mind from its former activities and slow the breathing rythmic. Inhaling for 3 seconds and exhaling for 3 seconds is a good way to regulate the flow of prana.

“As the movement patterns of each breath are observed as to duration, number, and area of focus, breath becomes spacious and subtle.”
Patanjali, CH-II, The Yoga Sutra

The यतगन [yogin] can then start to meditate by concentrating on the flow of पण [prāṇa : vital breath] flowing inside his body while observing his mind wandering and jumping from one thought to another. It is important not to try to force the mind to be still as it would add brain waves to the existing disturbing meditation.

The next step in meditation consists in repeating mentally a मन [mantra] while focussing on a focal point. Intellectual यतगन [yogin] shall focus on the Ajna क [cakra] (space between the eyebrows), whereas emotional यतगन  [yogin] shall use the Anahata क [cakra] (heart). The choice of the mantra also depends of the personnality of the यतगन [yogin]. It is important to choose a मन [mantra] devoted to a deity that fits with our state of mind. The ideal is to let the गर [guru] choose it but not all the गर [guru] are in position to attribute मन [mantra] so that I have for instance chosen my own मन [mantra]. As I identifie myself to the personality of तशव [śiva] on several points, my मन [mantra] is : “Om nama Sivaya”. I do not consider this मन [mantra] as a devotion to the god तशव [śiva] but its sonority, image and personality are full of meaning to me. यतगन  [yogin] who do not have a personalized मन [mantra] might meditate on the sound“om” or impersonal मन [mantra] such as “So-ham”. It is important neither to change the focal point nor the मन [mantra].

The mental repetition of a मन [mantra] synchronized with breath rythm lead to a state of harmony and pure thought. It is said that with a long practice, the knower, the knowledge and the known unify and the mind reaches the superconscious state of समतध [samādhi].

3.8. समतध - [samādhi]

“ For supreme happiness comes to the yogin whose mind is peaceful, whose
passions are at rest, who is stainless and has become one with god.”

Krsna, Chapter - VI : The Yoga of Meditation, Bhagavadgita

समतध [samādhi] is the ultimate stage of यग [yoga] leading to मक [mokṣa] and deliverance from sorrows and pains. समतध [samādhi] which aims at discriminating पकत [prakṛti : unconscious substance] from प रष [puruṣa : pure consciousness] is often apparented to a process of suppression of the mental activity. This goal is attained by concentrating on an object when, absolute union between the self and the object occurs. From this union between the knower and the known the यतगन [yogin] gets a perfect knowledge assimilated to god's knowledge. Thus, यग [yoga] is sometime defined as union with god.

“Yoga is hard to attain, I agree, by one who is not self-controlled it is attainable by striving through proper means.”
Krsna, Chapter - VI : The Yoga of Meditation, Bhagavadgita

How many यतगन [yogin] died without reaching समतध [samādhi] ? I don’t know, but most probably more than those who managed before dying. I have never approached the state of समतध [samādhi] but I think it is normal as I do not even practice enough. Sadasiva, my guru at the Sivananda Vedanta Centre himself confessed me that he has never attained samadhi in spite of several years of deep practice. What I appreciate is that on the contrary to sport, the यतगन  [yogin] neither breathe nor act for prestige, victory or समतध
[samādhi] but for peacefullness of mind. There is no competition at all as the single fact of practicing yoga is a source of happiness. This is exactly what कषण [kṛṣṇa] highlights as karma yoga to Arjuna in the Bhagavadgita.
What is more, the short-term benefits of meditation are multiple and easy to enjoy.
Some यतगन [yogin] considers that one hour of deep meditation equals 4 hours of deep sleep but nobody has never scientifically validated those kind of beliefs. Many other spernatural powers are attributed to यग [yoga], but I neither experienced nor believe in them. The following exerpts taken from the third chapter of Yoga-sutra highlights some of them :

“Focusing with perfect discipline on the perceptions of
another yields insight into that person’s consciousness.”

“Focusing with perfect discipline on the powers of an elephant,
or other entities, one acquires those powers.”

“Focusing with perfect discipline on the pit of
the throat eradicates hunger and thirst.”

“Focusing with perfect discipline on the
‘tortoise channel’, one cultivates steadiness.”

“Focusing with perfect discipline on the light in the crown
of the head, one acquires the perspective of the perfected ones.”

“Focusing with perfect discipline on the heart,
one understands the nature of consciousness.”

“By mastering the flow of energy through
the solar plexus, one becomes radiant.”

“By observing the aspects of matter - gross, subtle,
intrinsic, relational, purposive - with perfect
discipline, one masters the elements.”

Patanjali, CH-III, The Yoga Sutra

If मक [mokṣa : liberation] and समतध [samādhi] cannot be reached nor conceived by many yogi, we can wonder if this path is universal and if there is a sense in practising one limb independently from the others as it is commonly done in यग [yoga] schools around the world.
समतध [samādhi] or concentration is the ultimate stage of यग [yoga] leading to the union between the knower and the known and perfect knowledge assimilated to god's knowledge. Thus, यग [yoga] is sometime defined as union with god. Who is this god as it is conceived in the Yoga Sūtra of पञजतA [Patañjali] ? Is the aim of यग [yoga] incompatible with atheism or Christianity ?

The state of मक [mokṣa] can be defined as a state of freedom as liberation from ससर [sa ṃsāra] which is the cycle of birth, death, afterlife and rebirth. If the ultimate goal of मक [mokṣa] can be considered as universal in the Indian thought, it is far from being the case in the western conception of life and we can wonder what the aim of यग [yoga] becomes when it is practised by a self who does not live in ससर [saṃsāra].