Yesterday I referred to Anthony N. S. Lane's new primer, A Reader's Guide to Calvin's Institutes (Baker, 2009). I highly recommend this helpful small book.
It dawns on me that it might be helpful to comment on Calvin's aims in writing this famous theological treatise. The Institutes appeared in several different editions, over the course of several decades. Each edition included changes and additions by the author. Each edition tells something of Calvin's growing awareness of what he was writing for on the title page. In those days title pages were long and gave you the back thesis of the author. (How publishing has changed over the years!)
Embracing almost the whole sum of piety and whatever is necessary to know in the doctrine of salvation: A work most worthy to be read by all persons zealous for piety.
Calvin is saying that what he wrote was meant to be a brief summary of the Christian faith with the goal of edifying his readers so that they would embrace the truth about God's salvation.
In the 1536 edition Calvin also dedicated the volume to King Francis I in order to make an appeal that the king would end violence against the French Protestants. I find this so moving. Calvin wanted to see martyrdom end and he wrote theology to that end. His work was an apology for these Protestants and an appeal to the heart and mind of the king.
In a letter to the reader in the 1539 edition Calvin explains that the reader of the Institutes should use this material as a guide to the study of Holy Scripture and as a complement to his numerous commentaries on the various books of the Bible. Simply put, Calvin is richly biblical and deeply committed to encouraging readers to study the Bible itself, not Calvin. This connection warns us against a common mistake made by people who read Calvin. Some like his commentaries and some the Institutes. Calvin does not see them in conflict but as tools to be used together in order to understand the Holy Scripture.
In the French editions from 1541 to 1551 Calvin presents the Institutes as a guide to the laity in their study of the Bible. This underscores an earlier point I made. This work was intended for the ordinary reader, not specialists and professional theologians. It is "a summary of Christian doctrine." Calvin's goal was "lucid brevity." As long as the books seem he actually accomplishes this goal, making this still one of the most important tools anyone can read to better understand the Bible.