Callewaert started to publish long before the computer age, in 1974. He sent his PhD dissertation to the press typed on paper and then revised three typeset proofs. In 2009, he sent his most recent publication to the publisher on a memory stick: 2,187 pages. Many of the early articles, especially those of the pre-computer age, may no longer be easily available and for that reason eleven articles were selected and thoroughly revised for this publication (pp. 3-169). The research career of Callewaert was at the beginning strongly inspired by F. Camille Bulcke (Ranchi) and Charlotte Vaudeville (Paris). He followed their advice and worked mainly on manuscripts with Nirguna Bhakti literature, preparing critical editions and English translations. In order to complete the overall view of this research in that area, in this book are further given a summary of nine books published in the period 1989–2009 (pp. 171-216) and a summary of eight articles (1996–2011, pp. 217-44).
During his career he has photographed many manuscripts now threatened with destruction (the result is now digitized in the University of Heidelberg Library); he has prepared critical editions and translations in collaboration with several outstanding colleagues, and he realized how wrong he was in 1971 when defining his research future: to copy as many manuscripts as possible and to reconstruct the archetype, of “the original Kabir” and others, after a stemmatic comparison of the manuscripts. For, scribes committed errors, intentionally or unknowingly, and variant readings, Callewaert thought, should enable a researcher to establish the relationship between the manuscripts. What eventually turned out to be a wrong methodology became a very exciting adventure, when Callewaert started to discover the singers in the manuscripts. This evolution too is discussed in the present volume, From Chant to Script.