After his retirement from the University of Salzburg in 2000 Professor Winkler was delighted to volunteer for a few years as a senior lector in the American ITI (International Theological Institute). At that time it was still based at the former Carthusian Charterhouse at Gaming which Cardinal Schönborn of Vienna was pleased to transfer to Trumau near the Cistercian Abbey of Heiligenkreuz in Lower Austria in 2009. It was a novel experience to teach students in English who came from varying backgrounds all over the world, mainly from American colleges. As indispensable facts were a prerequisite to meet the needs of a well motivated audience Professor Winkler decided to write up a book suited for scholarly use. "In usum scholarum" is the result of his endeavours, now available in one paper-back volume. We hope it will please his English readers world-wide.