In his book, Caldwell proposed that there are Dravidian words in the Hebrew of the Old Testament, the archaic Greek language, and the places named by Ptolemy.

[5] Caldwell won a scholarship to Balliol College, Oxford only to find it rescinded when the authorities discovered that he had been born in Ireland.

[9] These wildly speculative claims, well outside the scope of linguistics, were intended "to develop a history which asserted that the indigenous Dravidians had been subdued and colonized by the Brahmanical Aryans".

He studied palm leaf manuscripts and Sangam literature in his search, and made several excavations, finding the foundations of ancient buildings, sepulchral urns and coins with the fish emblem of the Pandyan Kingdom.

[10] This work resulted in his book A Political and General History of the District of Tinnevely (1881), published by the Government of the Madras Presidency.

The publication of his research into both the languages and the history of the region, coupled with his position in both Indian and English society, gave stimulus to the revival of the Non-Brahmin movement.

He had adopted some of the methods of the Lutheran missionaries of earlier times, having learned German purely in order to study their practices.

[12] Caldwell the Tamil language scholar, Christian evangelist and champion of the native church,[13] remains today an important figure in the modern history of South India.

Pandian, visiting fellow at the Centre for the Study of Developing Societies in Delhi, recently commented that Caldwell’s "contribution to both Christianity in South India and the cultural awakening of the region is unmatched during the last two hundred years".