Sutra:
24. pUrvAchAryargaL ithil arththam aRivathaRku munbu, thangaLaip piRanthArgaLAka ninaiththirArkaL; ithil arththa gnyAnam piRantha pinbu *piRanthapin maRanthilEn engiRapadiyE iththai ozhiya vERonRAl kAlakshEbam paNNiyaRiyArkaL.

Meaning:
Purvacharyas starting from Sriman Nathamuni thought themselves as unborn, as in Thirumazhisai Azhvar's pasuram "anRu nAn piRanthilEn", until the time that they understood the meanings of the Thirumanthra. Once that knowledge was obtained, again as in Thirumazhisai Azhvar's pasuram "piRantha pin maRanthilEn" they would use nothing but the Thirumanthra in spending their time.

Sri PBA Swami's Sarartha Deepikai:
The greatness of the Thirumanthra in a general sense is being presented by Sri Pillai Lokacharya. As in Thirumzhisai Azhvar's pasuram "anRu nAn piRanthilEn" (I was not born then), purvacharyas such as Sriman Nathamuni, Alavandar and Ramanuja did not think themselves as born until the time that they understood the meanings of the Thirumanthra. Once they fully understand its meanings, as in Thirumazhisai Azhvar's pasuram "piRantha pin maRanthilEn" (once born I will not forget), they will not use anything but the meanings of the Thirumanthra in passing their time.

This pasuram occurs as the 64th in the Thiruccanthaviruttham by Thirumazhisai Azhvar. It states "anRu nAn piRanthilEn", because without true knowledge a soul has no essence. Once that knowledge is obtained from Him ("mayarvaRa mathinalam aruLinan"), the soul gains upliftment using it and this is stated as "piRantha pin maRanthilEn". That is, lack of Thirumanthra knowledge is lacking essence. And having the essence is the non-stop enjoyment of that knowledge.

Can one say that purvacharyas do not spend their time with anything but the Thirumanthra - do they not spend time with the Vedas, Sastras and Azhvars divine works? That is true. However, even when they spend time with those, it is done using the meanings of the Thirumanthra. Therefore, it is appropriate to state that they use only the Thirumanthra.