Pantanjali yoga sutras
The Yoga Sūtras of Patañjali are a collection of 196 Indian sutras (aphorisms) on the theory and practice of yoga. The Yoga Sutras were compiled prior to 400 CE by Patanjali who synthesized and organized knowledge about yoga from older traditions.

The Yoga Sūtras of Patañjali was the most translated ancient Indian text in the medieval era, having been translated into about forty Indian languages and two non-Indian languages.

Four pre-requisites:-

Power to discriminate real from unreal: (Viveka ) Wisdom gives inner strength and mental peace. A wise one gets no troubles. He is always on the alert. He never gets entangled in anything. He has farsightedness. He knows the true value of the objects of this universe. He is fully aware of the worthlessness of these shallow toys. Nothing, nothing can tempt him. Illusion’s cannot approach him now.

Discrimination is the faculty which distinguishes between the real and the unreal. The whole world outside and the universe that is inside, are unreal. Earth, water, wind, fire, the sky, the ocean, our bodies and the vital force animating them, our minds, our consciousness of ourselves all are but airy nothingness. The only real thing is the atman (self) or Brahman, the absolute.

Dispassion: (Vairagya) Wherever there is sensation of pleasure, the mind gets glued, as it were, to the object that gives pleasure. This is what is called attachment and brings only bondage and pain. When the object is withdrawn, or when it perishes, the mind suffers unspeakable pain. Attraction is the root cause for human suffering.

A dispassionate man has a different training and has different experience altogether. He is a past-master in the art or science of separating himself from the impermanent, perishable objects. He has absolutely no attraction for them and constantly dwells in the eternal. He stands adamant as a peak amidst a turbulent storm, as a spectator of this wonderful world show. A dispassionate man has no attraction for pleasant objects and no repulsion for painful ones. Nor is he afraid of pain. He knows well that pain helps considerably in his progress and evolution, in his journey towards the goal. He is convinced that pain is the best teacher.

Six qualities control of mind: (Shatsampatti ) tranquility, self-control, sense-control, forbearance, faith, and concentration.

Desire for emancipation: (Mumukshutva) An intense desire for liberation or deliverance from the wheel of birth and death with its concomitant evils of old age, disease, delusion and sorrow. If one is equipped with the previous three qualifications, viz., wisdom, dispassion and six virtues, Liberation will come by itself.

Notes: Yoga helps to control thoughts in mind field i.e thoughts (chitta,) mind (manas), intellect (buddhi) & Ego(ahamkara), mind-field (antakarana).
Manas is lower to -> anatahkarana(mindfield) is lower to -> mahat(buddhi) is lower to -> prakriti (guna balance)

The five-fold disturbance (vrittis) of the mind:

Pramana (right cognition): Pramana is that mode of mind, which apprehends an object as it is in reality. The marks of valid knowledge are novelty and correspondence. The valid sources of knowledge are perception, inference and testimony. Perception, inference and reliable testimony are the right cognition.

Viprayaya (false cognition): The second category of mental modifications is viprayaya or false knowledge; it is the false knowledge not corresponding with the form of external objects. Misconception is false notion, abiding in a form, which is not that of the subject. The example of viprayaya is nacre appearing like silver. Similarly, when the sounds or words are wrongly heard or the things are wrongly tasted or when through touch they are wrongly felt, all these are examples of viprayaya. Even such knowledge may or may not be accompanied by tensions and may or may not give rise to certain passions. Accordingly, it too will be coloured or colourless.

Vikalpa (imagination): The third category of mental modifications is vikalpa or imagination, which is defined as the cognition which follows the verbal knowledge, but which is not accompanied by any external data. Imagination is a notion founded on an idea conveyed by words, but of which there is no corresponding object (in reality).46 Much of the abstract thinking, daydreaming and ideation fall under this category. Even such abstract thinking etc. can be coloured or colourless.

Nidra (sleep): The fourth category of mental modifications is nidra or sleep. In sleep mind is considered to be usually inactive. However, Patanjali considers mind to be always in the state of flux, because its component forces by their very nature cannot remain inactive. Hence, Patanjali defines sleep as the mental modification based on the cognition of absence or void.

Smriti (memory): The last category of mental modifications is smriti or memory or remembrance, which is defined as the experienced objects or ideas not being completely robbed away from the mind. Remembrance is that function in which there is no trespassing beyond the object that has been cognized. Although all the experiences are momentary and one is robbed away of them just the next moment, yet they leave impressions in the mind and they cannot be fully forgotten. Mental activity of lingering on to such experiences is what is meant by the mental modification of smriti. The memories can be associated with certain tensions and thus may be colored or can be free of them and thus be colorless.

Notes:
Abhyasa & vairagya – dhyana and dispassion to control vrittis
After dispassion follows kaivalya (isolation)

Yamas: (Guidelines)

Ahimsa (non-injuring)
Satya (truthfulness)
Asteya (non-stealing)
Aparigarha (no greed or covetousness)
Brahmacharya (Abstinence/ celibacy)

Niyamas: (Duties)

Santosha (happiness)
Shaucha (purity)
Svadhyaya (study)
Tapas (self-discipline)
Isvarapranidhana (surrender/transcendence)

CONCLUSION:

Patanjali yoga sutras is all about yoga and maharishi patanjali’s take on workings of human body and how to control it by will, the working of universe and eternal consciousness. Its a must read for spiritual path and mastery of life. Gives practical exposure to lot of vedantic terms and concepts.