[The yoga of action] is for bringing about samādhi and for weakening the afflictions [to yoga].

Bryant Commentary:

Patañjali states here that by the performance of kriyā-yoga, the kleśas, afflictions—nescience, ego, attachment, aversion, and the clinging to life—which are the subject of the next sūtra, are weakened. Etymologically, kleśa, from the root kliś, means to torment, trouble, cause pain, afflict. The word is often translated as obstacles, since in addition to tormenting the living entities, the kleśas obstruct the mind from realizing the nature of the true self. As yoga was defined in I.2 in terms of the suppression of vṛttis, so here kriyā-yoga is defined in terms of the weakening, tanū-karaṇa, of what we will discover are the underlying cause of the vṛttis, the kleśas. We are thus moving into a deeper psychological level of the citta.

In fact the kleśas become like burnt seeds, scorched by the fire of discrimination, and thus they become unproductive, and one is no longer subject to these afflictions and the kliṣṭa (detrimental) vṛttis they produce. (We noted earlier that kliṣṭa is from the same root as kleśa.) In Vācaspati Miśra’s understanding, kriyā-yoga weakens the afflictions, at which point discrimination, no longer overcome by these powerful enemies, can manifest and burn them further. Otherwise, the kleśas are present at all times. Without performing kriyā-yoga, says Śaṅkara, one may know theoretically from the scriptures and the teachings of the gurus that prakṛti and puruṣa are different, but this type of knowledge in and of itself will not remove the kleśas, and thus there will be no experiential realization of these theoretical ideas. Consequently, one will remain victimized by these kleśas—ignorance, ego, desire, etc. Hence Patañjali is prescribing that one must actively perform kriyā-yoga.

Recall that under normal circumstances, every seed of karma must at some point bear its fruit. Since there are unlimited seeds of karma, which cannot all fructify during a single lifetime, one must be reborn in order to experience all one’s just karmic fruits lying in storage. Upon being reborn and experiencing the fruits of these previously stored seeds of karma, however, more actions are performed in response, each one planting more seeds of karma, and the vicious cycle of birth and death is perpetuated. As has been discussed, any single action triggers a potentially unending series of reactions, since one solitary action produces a reaction, which, when it eventually bears fruit, prompts a response or rereaction, prompting a rerereaction, provoking a rererereaction and so on unlimitedly. By kriyā-yoga, these seeds are burnt and so no longer ripen and bear the fruit of repeated experiences in the world of saṁsāra. Simultaneously, as the kleśas are weakened, sattva is enhanced, and, as this happens, the discrimination of the difference between the puruṣa soul and prakṛti matter can arise.

Some scholars feel that the jump in subject matter from the previous chapter on samādhi to the kriyā-yoga orientation of this chapter points to the patchwork nature of the text. After all, the path to samādhi was defined earlier as stilling the mind, and here as actively engaging in devotion, austerity, and study. As Feuerstein (1979) has long argued, however, there is an organic transition and fundamental structural coherence between the two. Sūtra I.2 defines the primary goal, citta-vṛtti-nirodha, the pacification of the mind, and II.1ff concern themselves with those subconscious mechanisms triggering these vṛttis, the kleśas. The distinction in terminologies and practices in this chapter merely reflects the requirements of a deeper level of psychological analysis and subsequent remedial activity. This chapter is thus an indispensable continuation of the first, providing more specific technical information as to the psychological mechanisms underpinning the citta-vṛttis that sūtra I.2 requires the yogī to still. Without eliminating the kleśas, there is no question of bringing about this ultimate state, samādhi-bhāvana.

For Bringing About Samadhi And Minimising The Klesas.

Its purposes are to disarm the causes of suffering and achieve integration.

These practices cultivate an attitude conducive to being absorbed in Spirit and minimize the power of the primal causes of suffering.

(Kriya-Yoga) is practised for attenuating Klesas and bringing about Samadhi.

Taimini Commentary:

Although the practice of the three elements of Kriya-Yoga is supposed to subserve the preparatory training of the aspirant it should not therefore be assumed that they are of secondary importance and have only a limited use in the life of the Sadhaka. How effective this training is and to what exalted stage of development it is capable of leading the aspirant will be seen from the second Sutra which we are considering and which gives the results of practising Kriya-Yoga. Kriya-Yoga not only attenuates the Klesas and thus lays the foundation of the Yogic life but it also leads the aspirant to Samadhi, the essential and final technique of Yoga. It is, therefore, also capable of building to a great extent the superstructure of the Yogic life. The importance of Kriya-Yoga and the high stage of development to which it can lead the Sad 120 haka will be clear when we have considered the ultimate results of practising Tapas, Svadhyaya and Isvara–Pranidhana in II-43-45.

The ultimate stage of Samadhi is, of course, reached through the practice of Isvara-Pranidhana as indicated in I-23 and II-45. Although the two results of practising Kriya-Yoga enumerated in II-2 are related to the initial and ultimate stages of Yogic practice they are really very closely connected and in a sense complementary. The more the Klesas are attenuated the greater becomes the capacity of the Sadhaka to practise Samadhi and the nearer he draws to his goal of Kaivalya. When the Klesas have been reduced to the vanishing point he is in habitual Samadhi (Sahaja-Samadhi), at the threshold of Kaivalya.

We shall take up the discussion of these three elements of Kriya-Yoga as part of Niyama in II-32.

The practice of yoga reduces afflictions and leads to samadhi.

Iyengar Commentary:

By reducing afflictions to a minimum or even eradicating them, kriyayoga promotes profound meditation, which is a precursor to samadhi. The purpose of this yoga is to minimize all impediments to meditation and thus bring the intelligence to full, vibrant life.

They help us minimize obstacles and attain samādhi.

Satchidananda Commentary:

Here, Patañjali explains why Kriyā Yoga should be practiced: to minimize obstacles and to get into samādhi. He puts everything in very simple terms, but we should know and remember the vital importance of Kriyā Yoga. Without it we can never overcome the obstacles and reach samādhi. Mainly, all we do in the name of Haṭha Yoga, Japa Yoga, living in Yoga institutes and āśrams is all part of our Kriyā Yoga—our preparation for meditation and samādhi.

(They are for) the practice of Samadhi and minimising the pain-bearing obstructions.

SV Commentary:

Most of us make our minds like spoiled children, allowing them to do whatever they want. Therefore it is necessary that there should be constant practice of the previous mortifications, in order to gain control of the mind, and bring it into subjection. The obstructions to Yoga arise from lack of this control, and cause us pain. They can only be removed by denything the mind, and holding it in check, through these various means.

The Yoga of action is certainly to be performed, ‘ for the purpose of bringing about trance and for the purpose of attenuating the afflictions/ It is that which being performed, brings about trance and attenuates ihe afflictions. The afflictions thus attenuated become characterized by unproductiveness. When their seed power lias, as it were, been singed by the fire of High Intellection ; and for this reason the mind after their attenuation, is never again touched by the affliction; and having by subtle cognition come up to the discrimination of the distinct natures of the Puru’sa and Objective Essence, has the whole of its duty fulfilled and can only resolve into its cause.

~ Rāma Prasāda translation.