The citta is thus the background of the mind. It is like a lake on which rise and fall waves, which are comparable to the thoughts. These thought waves are called vrittis. A vritti is a ‘mental whirlpool’, or mental modification; it is the difference between action and the absence of action in the mind. In the average person there are thousands of vrittis arising each minute in the mind. It is impossible for the conscious mind to keep track of the minute and intricate changes through which the mind is traveling every second. It is no surprise, therefore, that it takes many years of observation of ones own mind to understand its workings.

The Self is the witness of all that is perceived, but it neither acts nor reacts, for all action and reaction take place in the mind, appearing as vrittis. Thought, the most powerful force in the universe, initiates all action. Activity carried out on the physical plane is only a mirror of the inner workings of the mind. That which is assumed to be reality, the physical environment in which each person lives, is only a projection of the mind. In truth, when the many mental modifications, vrittis, are restrained, one is no longer affected by the comings and goings of the world, and the Self shines forth in undisturbed purity.

Source Text	Approx. Date	Definition of Yoga
Katha Upanishad	c. 5th century BCE	“When the five senses, along with the mind, remain still and the intellect is not active, that is known as the highest state. They consider yoga to be firm restraint of the senses. Then one becomes un-distracted for yoga is the arising and the passing away” (6.10-11)
Bhagavad Gita	c. 2nd century BCE	“Yoga is said to be equanimity” (2.48); “Yoga is skill in action” (2.50); “Know that which is called yoga to be separation from contact with suffering” (6.23).
Yogācārabhūmi-Śāstra (Sravakabhumi), a Mahayana Buddhist Yogacara work	4th century CE	“Yoga is fourfold: faith, aspiration, perseverance and means” (2.152)
Yoga Sutras of Patanjali	c. 4th century CE	“Yoga is the suppression of the activities of the mind” (1.2)
Vaisesika sutra	c. 4th century BCE	“Pleasure and suffering arise as a result of the drawing together of the sense organs, the mind and objects. When that does not happen because the mind is in the self, there is no pleasure or suffering for one who is embodied. That is yoga” (5.2.15-16)
Yogaśataka a Jain work by Haribhadra Suri	6th century CE	“With conviction, the lords of Yogins have in our doctrine defined yoga as the concurrence (sambandhah) of the three [correct knowledge (sajjñana), correct doctrine (saddarsana) and correct conduct (saccaritra)] beginning with correct knowledge, since [thereby arises] conjunction with liberation….In common usage this [term] yoga also [denotes the soul’s] contact with the causes of these [three], due to the common usage of the cause for the effect. (2, 4).
Kaundinya’s Pancarthabhasya on the Pasupatasutra	4th century CE	“In this system, yoga is the union of the self and the Lord” (I.I.43)
Linga Purana	7th-10th century CE	“By the word ‘yoga’ is meant nirvana, the condition of Shiva.” (I.8.5a)
Brahmasutra-bhasya of Adi Shankara	c. 3rd century BCE	“It is said in the treatises on yoga: ‘Yoga is the means of perceiving reality’ (atha tattvadarsanabhyupāyo yogah)” (2.1.3)
Mālinīvijayottara Tantra, one of the primary authorities in non-dual Kashmir Shaivism	6th-10th century CE	“Yoga is said to be the oneness of one entity with another.” (MVUT 4.4–8)
Mrgendratantravrtti, of the Shaiva Siddhanta scholar Narayanakantha	6th-10th century CE	“To have self-mastery is to be a Yogin. The term Yogin means “one who is necessarily “conjoined with” the manifestation of his nature…the Siva-state (sivatvam)” (MrTaVr yp 2a)
Yogabija, a Hatha yoga work	14th century CE	“The union of apana and prana, one’s own rajas and semen, the sun and moon, the individual soul and the supreme soul, and in the same way the union of all dualities, is called yoga. ” (89)
Śaradatilaka of Lakshmanadesikendra, a Shakta Tantra work	11th century CE	“Yogic experts state that yoga is the oneness of the individual soul (jiva) with the atman. Others understand it to be the ascertainment of Siva and the soul as non-different. The scholars of the Agamas say that it is a Knowledge which is of the nature of Siva’s Power. Other scholars say it is the knowledge of the primordial soul.” (SaTil 25.1–3b)

The Yoga Sūtras of Patañjali define the essence of yoga as follows:
योगश्चित्तवृत्तिनिरोधः || 1.2 ||
Yogaś citta-vṛtti-nirodhaḥ

English: Yoga is the restriction of the fluctuations of consciousness.
German: “Yoga ist das Zuruhebringen (Nirodha) der Fluktuationen (Vritti) des Bewußtseins (Chitta).”

Furthermore Patañjali states:
तस्यापि निरोधे सर्वनिरोधान्निर्बीजः समाधिः || 1.51 ||
Tasyāpi nirodhe sarva-nirodhān nirbījaḥ samādhiḥ

English: Nirbiija samadhi is attained once even these impressions have become tranquil and when everything has become tranquil.
German: “Wenn selbst diese (neuen unterbewußten Eindrücke) zur Ruhe kommen, kommt alles zur Ruhe, (und daraus entsteht) die keimlose Versenkung (Nirbija samadhi).”

It needs to be emphasised that the translation of Sanskrit into other languages is extremely difficult. These difficulties exceed the ‘normal’ hermeneutical difficulties associated with the interpretation of ancient texts. The Sanskrit language is very special in that it is specifically designed to express the ineffable. It has a rich psychological vocabulary which allows to communicate states of consciousness which are virtually unknown to the Western mind. Next to its semantic complexity phonetics plays a crucial role, i.e., the sounds/vibrations produced by the Sanskrit language convey a dimension of meaning which cannot be reduced to its lexical and syntactic properties. Interestingly, neuroscience has recently shown that different aspects of language are hemispherically lateralised (the hemispheric lateralisation of language). For instance, Nobel laureate Roger Sperry’s classical studies on split-brain patients have shown that the left hemisphere is predominantly responsible for lexical and syntactic elements of language processing (grammatical rules, sentence structure, et cetera). Per contrast, the right hemisphere preferentially processes prosodic and emotional aspects of speech and language. These neuro-anatomical asymmetries therefore provide important insights into the way language and speech are processed in the brain. Furthermore, they neuro-anatomically support the claim that the prosody of the Sanskrit language is essential in order to fully grasp its meaning, both intellectually and emotionally. In India, the aphorisms are chanted in a very specific melodic manner.

yoga-sutras-of-patanjali-swami-vivekananda