nAyanArAchAn piLLai is a great scholar and is the dear son/sishya of periyavAchAn piLLai. He authored one of the most important granthams of our sampradhAyam - charamOpAya nirNayam (http://ponnadi.blogspot.in/p/ charamopaya-nirnayam.html) which establishes the divine glories of emperumAnAr (srI rAmAnuja). Please read this recent article which gives a glimpse of nAyanArAchAn piLLai's glories at http:// guruparamparai.wordpress.com/2013/04/21/nayanarachan-pillai/.