Samkhya-Yoga-Kundalini
The niyamas are:
Śaucāt-sva-aṅga-jugupsā parair-asaṁsargaḥ
Through purification, [the yogi develops] aversion to his own body [and the desire for] non-association with others.
Through the practice of yoga, the yogi begins to lessen the desire for gratification of the senses. The desire for non-association flows naturally from the desire to cure old bad habits. There are different degrees of this. The most extreme is the ascetic who lives alone and prefers to maintain a solitary existence. More common are monks and others who live in communities with other like-minded individuals. Even among these there are different degrees of isolation from the outside world. In secular society it is found in people who are recovering from alcohol and drug addiction, who are advised to cut off their association with others who are still actively involved in their vices.
Sattva-śuddhi-saumanasya-aikagrya-indriya-jaya-atma-darśana-yogyatvāni ca
[Through] purity of sattva, [the yogi gains] a calm mind, and the ability to concentrate, to subdue the senses, and to know the atma.
Sattva requires explanation. In the world view that was common when the Sutras were written, it is one of the three guna or qualities that exist throughout material nature:
The guna are said to combine in different proportions to produce the various forms of nature. It may be helpful to think of sattva and tamas as opposite ends of a spectrum, such as good and evil or light and darkness. The activity of rajas can vary both along the spectrum of tamas to sattva, and also in a range from low to high.
In the current context, the harmful impulses, thoughts, and actions related to lust, anger, and greed are tamas. The yogi needs to adjust his thoughts and control his impulses toward the sattva end of the spectrum. When he does that he starts to realize the benefits of calm mind, etc. These read like the steps of a ladder that the yogi is climbing. Note: sattva can never be completely pure. The three guna are said to be inseparable, and all three are always present to some degree.
Santoṣad-anuttama-sukha-lābhaḥ
Through contentment, [he gains] unsurpassed happiness.
No explanation or elaboration required, only contemplation.
Kāya-indriya-siddhir-aśuddhi-kṣaya-attapasaḥ
From austerity, [he gains] perfection of the body and the senses and the diminishing of impurity.
What kinds of austerity bring about perfection of the body and the senses? Surely not things like fasting, subjecting oneself to extremes of hot and cold, etc. One good example is getting up early in the morning to practice yoga.
Svādhyayād-iṣṭa-devatā-samprayogaḥ
From chanting of mantras, [he gains] contact with the desired deity.
Svadhyaya has a few different meanings. It is sometimes translated as self-study, and people derive all sorts of meaning from that. Svadhyaya can also refer to the practice of memorizing and reciting scriptures for the purpose of transmitting them to others that was used before writing was commonplace. Here, svadhyaya refers to the chanting of mantras that are associated with specific deities. This type of practice is common in Buddhism but is usually omitted by western yoga practitioners. Compared to Isvara, the ista-devata are lesser deities.
Samādhi-siddhir-īśvara-praṇidhānāt
From Isvara-pranidhana, [the yogi] attains samadhi.
The explanation of Isvara and Isvara-pranidhana is given in Yoga Sutras chapter one, and is presented here in abbreviated form.
Īśvara-praṇidhānād-vā
In Sutra 1.23 Isvara-pranidhana is introduced with the word va, meaning “or”. This implies that isvara-pranidhana is being offered as an alternative to the more detailed methods of samadhi described in the Jnana portion of the Sutras.
The sutras go on to describe some characteristics of Isvara:
Patanjali has described isvara-pranidhana as repetition of the syllable “Om” and contemplation of its meaning.
There is some disagreement among translators regarding the first phrase. Here it is taken to mean changing the consciousness, which is usually directed outward, and directing it inward. The second phrase tells us that, along the way to attaining samadhi, isvara-pranidhana helps the yogi to overcome obstacles that may be in his/her path. That seems like the same thing as eliminating impurities and it is, but there are differences to what has been discussed in yama and niyama. This will be discussed elsewhere.
The subject of Isvara is deep and wide. It is often interpreted as referring to Saguna Brahman, the universal unity that is central to Advaita Vedanta, which is the dominant philosophy of Hinduism. The Samkhya-Yoga tradition, of which the Yoga Sutras is a part, describes a different type of Isvara. If the reader is not comfortable with Patanjali’s concept of Isvara, it is acceptable to substitute his/her own concept of God. Isvara will be discussed at length elsewhere.