Four noted Brahmin writers of the Vijayanagara empire, Kumara Vyasa, Timmanna Kavi, Kumara Valmiki and Chatu Vitthalanata proliferated the "shatpadi" metre in their versions of the Hindu epics. Inspired by the "Vachana" writers who used the song-prose medium to write their poems, the Haridasa poets used genres such as the "kirthane" (musical compositions with two refrains – composition based on "raga", or tune and "tala", or rhythm), the "Suladi" (rhythm-based) and the "Ugabhoga" (melody-based) to convey their devotion to God. Their contributions to the south Indian classical music (Carnatic music) is well acclaimed, Purandaradasa and Kanakadasa being the most popular poets of this cadre. Purandaradasa was the most prolific Haridasa poet who wrote in the "ragale" metre and also earned the honorific "Karnataka Sangeeta Pitamaha" ("Father of Carnatic music"). Kanakadasa was versatile in many native metres. His "Mohana tarangini" is in the "sangatya" metre, "Nalacharita" and a book of morals for children called "Haribhakti-sara" are in the "shatpadi" metre.