Most of what we know about Carnatic music, comes from great mansucripts and commentaries authored by great musicologists of the past. Mahavidvans like Venkatamakhin, Somanatha, Ramamatya, Sarngadeva e.t.c. greatly enriched the knowledge base of our artform, and their writings formed the very base of Carnatic musicology. Today, we shall speak briefly about the content and nature of three select manuscripts that arguably define Carnatic music even today.