Bhagavad Gita Verse 27, Chapter 4

sarvaaneendriyakarmaani praanakarmaani chaapare |
aatmasaiyamyogaagnau juvhati jnyaanadeepite || 27 |
 
Others offer the activities of the senses and the activities of the life force into the flame of the discipline of self-restraint, kindled by knowledge.
 
sarvaani : all
indriya-karmaani : activities of the senses
praana-karmaani : activities of the life force
cha : and
apare : others
aatmasaiyam : self-restraint
yogaagnau : flame in the form of discipline
juvhati : offer
jnyaana : knowledge
deepite : kindled by
 
In prior shlokas, Shri Krishna gave us a variety of techniques to practice yajnya, from worship of a deity to more advanced techniques such as contemplation of the eternal essence, restraining movement of senses, and dissolving the notion of external objects altogether. In this shloka, he describes a technique for more advanced seekers where one not just restrains the senses, but also restrains the life forces or praana within our body. This discipline is the raaja yoga of Patanjali. It begins with the three limbs of yama, niyama and aasana that we saw in the previous sholka. Let us examine one key aspect of this technique, which is understanding of praana.
 
Praanaas are energy systems within our body that sustain physiological processes. There are five types of praana : praana, apaana, udaana, vayaana and samaana. Just like restraining the senses conserves energy that can be redirected towards advancing spiritually, so too can restraining the praanaas lead to the same outcome. However, this technique requires the guidance of a teacher and is not recommended for self-experimentation.
 
The senses and the praanaas are like rays of the sun emanating from our self. So as the yogi progresses in this yajnya, he regulates the praanaas using praanaayaam, the fifth limb of the raaja yoga technique which is described a later shloka. He then withdraws attention from senses and from the praanas, and redirects the energy towards concentration or dhyaana on the eternal essence, which is the sixth limb of Patanjali yoga. He then progresses to uninterrupted concentration or dhaarana, the seventh limb. Eventually, he attains direct perception of the eternal essence. This ultimate state is known as samaadhi, the eight and final limb of Patanjali yoga.
 
Knowing fully well that most of us need more basic techniques, Shri Krishna gives us a whole range of options in the next shloka.