His mission of explaining the essential principles through gIthA is also a wonderful revelation of his mastery. arjuna was raring to go and fight it out with the kauravas. But seeing bhIshma pithAmaha, dhrONAchArya, krupAchArya, dhuryOdhana, etc - who are all related to him one way or the other, he got bewildered. He started shivering out of fear for killing his own kith and kin, teachers and mentors. He dropped his famous/powerful bow named gANdIpam and took full shelter of krishNa. krishNa, having masterfully presented such situation to arjuna, took that opportunity to become gIthAchArya and explained the nature of thathva thrayam (chith, achith, Isvara), karma yOgam, gyAna yOgam, bhakti yOgam, his own opulences (viswarUpam and vibhUthi yOgam), the 3 modes of nature (sathvam, rajO, thamO guNams), etc and completes gIthA with the final verdict on total surrender to himself. Thus, bhagavAn sets up arjuna so that he too can take the role of AchArya and explain the essential principles in a crystal clear way that can be understood by every one. This principle of his liking towards being an AchAryan is highlighted by piLLai lOkAchAryar beautifully in srIvachana bhUshaNa dhivya sAsthram in sUthrams 430 and 431. In these 2 sUthrams, he first explains that "bhagavAn also likes to assume the role of AchAryan" and then he goes on to say "that is why he assumed the role of the first AchAryan in guru paramparai and spoke bhagavath gIthA to arjuna and protected vibhIshaNAzhwAn before rAma-rAvaNa war (explaining the principle of sharaNAgathi)". Eventually, he helps arjuna (and all his brothers and family) in so many ways and ensure that they are well taken care off by enacting so many wonderful situations like hiding the sun to kill jayathradha, etc.
A divine event that happens in thirukkaNNamangai dhivyadhEsam is highlighted in periya thirumozhi 7.10 padhigam where in the last pAsuram, thirumangai AzhwAr says to emperumAn that he can become his sishya and learn the meanings of his thirumozhi pAsurams. To fulfill those words, emperumAn becomes periyavAchAn piLLai (born on AvaNi rOhiNi and named krishNa) and thirumangai AzhwAr becomes nampiLLai (born on kArthigai kArthigai and named thirukkalikanRi dhAsar). periyavAchAn piLLai becomes a dear sishya of nampiLLai, learns all the essential principles (that are coming down via our AchArya paramaparai centered on srI rAmAnuja) from him and shows great regard and affection for his AchArya.
He brings out the most important principles of srI rAmAyaNam for us. The sargam related to vibhIshaNa sharaNAgathi is explained by him in great detail analysing the aspect of sharaNAgathi in the most brilliant way. Let us see an example for his brilliance in writing commentaries by going through his commentary for just one phrase in a particular slOkam in sundhara kANdam 21st sargam 3rd slOkam.
- As it is customary and necessary to give a seat to kings before speaking, she places the grass there. Also, she thinks that "if I speak to him pleasingly, he may show some mercy on me and leave". Since it is said that when there is no seat (chair), just bhUmi (earth), water or grass can be offered as seat - sIthA pirAtti offers grass as a seat.
- When a lady welcomes another man directly - that means she is treating him as an outsider (instead of giving a side glance to some one like her husband or lover). So, sIthA pirAtti thinks if she directly speaks to him (by offering a seat in the form of the grass), rAvaNa will understand that she is not interested in him and thus will leave her.
- Since hanuman was watching from the top of the tree she puts a grass in between herself and rAvaNa. It is said that water or grass can be placed to highlight a line of separation between two parties.
- It is said that women cannot directly see or interact with outsiders (men). So, she places the blade of grass which can be considered as a mediator between herself and rAvaNa.
- When rAvaNa was given good advice by akampanan, mArIchan, mAlyavAn, etc., he ignored them since he was leading himself and the other rAkshasas into the path of destruction. So, she places the blade of grass to indicate to him that he is just like the blade of grass which does not have the capacity to listen to good instructions.
- Instead, she thinks that she will make this blade of grass listen to the good advice as she has the purity to even make a blade of grass understand her instructions.
- She thinks that seeing the blade of grass gaining knowledge and becoming as good as a chEthana (sentient being), rAvaNa will understand her power and leave her out of fear.
- She considers rAvaNa as good as the blade of grass (which lacks any knowledge).
- As the blade of grass is not harming her like rAvaNa does, she considers him even lower than the grass.
- As said in "gyAnEna hIna: pasubi: samAna:" - one who is deficient in knowledge is considered as an animal only, she places the grass so rAvaNa (who is as good as an animal) can eat it.
- She considers rAvaNa as a fox and srI rAma as a lion. She also says "You are as good as a rabbit which lacks valour" before. So, she says only srI rAma deserves to enjoy me and you deserve to enjoy only this grass.
- As rAvaNa spoke highly of his opulence (like great jewels, gems, clothes, etc), she responds saying "I consider your opulence as good as this blade of grass".
- She says I am holding on to my life only in the hope that srI rAma will come and rescue me. If not for that, I consider my life as good as this grass only and I will give it up quickly.
- She makes fun of rAvaNa saying "Due to your faults, this lankA is going to be burnt down. At that time you can use this blade of grass to build a hut and live there".
- There is a nyAyam called "thruNOlapa nyAyam" - which means a plant which looks small eventually becomes a creeper. She instructs "give up your attachment towards me and turn your attention towards your wife". Also she says "give up normal activities like attachment towards woman and develop special activities like surrendering unto srI rAma's lotus feet".
- When sIthA says "surrender to srI rAma", rAvaNa asks "how will he forgive me for my mistakes?". She replies "Just like the blade of grass when placed in the ocean, will be pushed out to the shores by the waves, srI rAma will also ignore your mistakes and accept you".
- She says "Just like I put down this blade of grass, you drop your anger, pride, etc., and surrender to srI rAma to be saved".
- She says "If you want to save yourself and your family, belongings, etc., you grasp this blade of grass with your mouth and surrender unto srI rAmA who is epitome of manliness". Grasping the grass with the mouth is considered as a very humble act.
- To indicate that she can convert this grass into a pillar and bring out rAghavasimham to break the chest of rAvaNa.
- It is normal to take vows by throwing grass or sand. Here she takes a vow saying srI rAma who is accompanied by lakshmaNa will destroy you through his arrows and will not even have to touch you physically to accomplish that.
- As "kruthvA" means "pluck" per its etymology, she says just like I plucked this grass, srI rAma will pluck your head and kill you.
- As it is said in sAsthram "When a brAhmaNa (virtuous person in this context) is tortured by abhrAmaNa (non-virtuous person in this context), his parts can be destroyed", when sukrAchArya troubled vAmanan emperumAn, emperumAn used a blade of grass to pierce his eyes. Similarly, I will pierce your eyes since you have seen the wife of another person with wrong attitude.
- When kAkAsura committed abominable offense towards sIthA pirAtti, srI rAma, plucked a grass and converted that to brahmAsthram and destroyed kAkAsura's eye. Similarly, she says "I will pierce your eyes with this grass".
- nara-nArAyaNa rishis are special incarnations of emperumAn as sishya-AchArya. Of these two, nArAyaNa rishi killed a king named dambOdhbavan using a grass. Similarly, I will kill you using this blade of grass.
- I am mercifully not burning you down with my chastity (pure devotion towards srI rAma). If you continue this torture, I will use this grass to light the fire of my chastity and will burn you down in to ashes.
- As "kruthvA" means "pluck" per its etymology, she says she will pluck his head just like she plucked the grass.
The first krishNa we saw here is bhagavAn himself - he is common for both bandham (bondage) and mOksham (upliftment) as he is supremely independent. He can either grant us mOksham (out of his mercy) or keep us in samsAram (due to our karmA and his commitment to oblige by sAsthram). But the second krishNa (periyavAchAn piLLai) is only focussed on the upliftment of jIvAthmAs. AchAryas are totally dependent on bhagavAn and their goal is to purify jIvAthmAs and bring them to bhagavAn for his service. So, obviously we are more attached and indebted to AchAryas and always approach bhagavAn through these glorious AchAryas.
Notes: Thanks to puthUr krishnaswamy iyengar swamy's detailed yet simple explanation of thanislOkam vyAkyAnam.