Typically when someone says "Yagnya" (or "Yajna"), we visualize following or something similar:
To avoid such impression, many translators use the word "sacrifice", which is also famous in various Sanskrit dictionaries.
But, then we imagine following:
In this case, Shri Krishna is not talking about such limited scoped aspects. Because, in today's time, it will be easily rejected by the most populace, as such activities don't render anything.
- "Homa Havana" is only 1 type of "Yajna", but not all
- "Bali/Ahuti" is only 1 type of "Sacrifice", but not all
Anyone resorting to such activities in today's time, might be considered TAmasik (ignorant), if done blindly.
He is talking about all the eras, past-present-future.
The correct interpretation for lord's words about "Yajna / sacrifice" should be "To put Efforts", viz. endeavour.
Keeping this in mind, let's see better translations of this verses by Gambhirananda:
BG 3.11 - You nourish the gods with this. Let those gods nourish you. Nourishing one another, you shall attain the supreme good.
BG 3.12 - Being nourished by sacrifices (i.e. efforting), the gods will indeed give you the coveted enjoyments. He is certainly a theif who enjoys what have been given by them without offering (these) to them.
BG 3.13 - By becoming partakers of the remembers of sacrifices, they become freed from all sins. But the unholy persons who cook for themselves, they incur sin.
Here it's also important to note that "Deva" means those natural elements, which have divine properties (Daivi sampadA). Certain combinations of 5 elements water, fire, earth, air, wind -- are considered divine. Ex: river, mountain, rain, wind, cows/animals, parents, ...
In brief, the lord is suggesting to appropriately contribute in running the "Nature cycle".
In old times, there were different sacrifices to preserve these divine cycles. In modern times, we are supposed to sacrifice our laziness & ignorance to achieve same objective.
One interpretation may look as following:
- 3.11 -- If we put efforts in planting trees, save water, avoid various pollution, then the rain cycle (Varuna deva) and wind cycle (VAyu deva) will be preserved;
- 3.12 -- These natural elements will in turn give us good crops & refreshing air for better livelihood; Those people who pollute these elements for short term gain are thieves, because they lack efforts in the preserving the system
- 3.13 -- Those who eat after working their jobs (i.e. sacrificing leisure), would become free from related sins (e.g. cutting crops or killing animals for their food); But those who don't work in this social structure, would be incurring sin
Beyond the "Nature cycle", I think these verses can be interpreted for all the "Systems", which are supposed to be run well. Every contributor has to act their duty to be able to benefit fairly from the system.
These systems can be family, society, nature, office, or anything.