The institutes begins with some words for the reader. After many years of careful refinement since the first edition (1536) Calvin has now (1559) provided something that all of you will approve with the following intent
to benefit the church by maintaining the pure doctrine of godliness
to prepare and instruct candidates in sacred theology for the reading of the divine Word, in order that they may be able both to have easy access to it and to advance in it without stumbling. For I believe I have so embraced the sum of religion in all its parts, and have arranged it in such an order, that if anyone rightly grasps it, it will not be difficult for him to determine what he ought especially to seek in Scripture, and to what end he ought to relate its contents. If, after this road has, as it were, been paved, I shall publish any interpretations of Scripture, I shall always condense them, because I shall have no need to undertake long doctrinal discussions, and to digress into commonplaces. In this way the godly reader will be spared great annoyance and boredom, provided he approach Scripture armed with a knowledge of the present work, as a necessary tool. But because the program of this instruction is clearly mirrored in all my commentaries, I prefer to let the book itself declare its purpose rather than to describe it in words.
In other words we have the product of lifelong, prayerful consideration of the scripture written in the face of much hardship and opposition. A noble purpose and an enduring legacy. A summary of the Bible's doctrine in order that we may walk in the obedience of friendship with God.