"en thIrththanE!", says nammaazhvaar

From the Bhakti List Archives

• April 14, 1995


Dear bhakti group,

I chanced upon the following paasuram on nammaazhvaar
yesterday night:

ovaath thuyarp piRavi utpada maRRev evaiyum,
moovaath thani muthalaay moovulakum kaavalOn,
maavaagi aamaiyaay mIn aagi maanidam aam,
thEvaathi thEva perumaa Nnen_thIrththanE.	2.8.5

I was hoping someone could shed light on why aazhvaar
addresses perumaaL as his "thIrththan" in the last line. 
What exactly is he saying? I don't know of any temple
where the deity is known as thIrththan, nor does it
seem particularly appropriate for the word to simply mean
the "sanctifier" or "sanctified". 

If anyone has any ideas, pleas respond.

Yours,
Mani