 For the second edition , published in 1539 , Calvin dropped this format in favour of systematically presenting the main doctrines from the Bible . In the process , the book was enlarged from six chapters to seventeen . He concurrently worked on another book , the Commentary on Romans , which was published in March 1540 . The book was a model for his later commentaries : it included his own Latin translation from the Greek rather than the Latin Vulgate , an exegesis , and an exposition . In the dedicatory letter , Calvin praised the work of his predecessors Philipp Melanchthon , Heinrich Bullinger , and Martin Bucer , but he also took care to distinguish his own work from theirs and to criticise some of their shortcomings . 
