He composed a grammar of High Tamil, and was the first to write a grammar of Low Tamil (the common dialect) which still remains the foundation of scientific Tamil philology. He is also the complier of several Tamil dictionaries, among them the quadruple lexicon containing words, synonyms, categories of words, and rhymes; a Tamil-Latin and Latin-Tamil-Portuguese dictionary.
He wrote several ascetical books in Tamil, especially doctrinal instructions for the use of the native catechists; also controversial tracts against the Danish Lutheran missionaries who sought to gain a foothold in the Mandura Mission. Beschi is, however, best known as a Tamil poet. In a poem of 1100 stanzas, "Kittêri ammalle saritiram" he sings the praises of the martyr St. Quiteria (not St. Catherine, as some writers have mistakenly asserted). His greatest poetical work is the "Tembavani" (The Unfading Garland), one of the Tamil classics.
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