#2 The Analogy of the Scriptures (Analogia Scripturae)
Here is Richard A. Muller’s definition of analogia Scripturae: “the interpretation of unclear, difficult, or ambiguous passages of Scripture by comparison with clear and unambiguous passages that refer to the same teaching or event.” An example of this would be utilizing a passage in Matthew to help understand a passage dealing with the same subject in Mark. This principle, as with the first one, obviously presupposes the divine inspiration of Scripture.
The principle of analogia Scripturae gained confessional status as follows: “The infallible rule of interpretation of scripture is the scripture itself . . .” (2LCF 1.9).
 Richard A. Muller, Dictionary of Latin and Greek Theological Terms (Grand Rapids: Baker Book House, 1985, Second printing, September 1986), 33; emphasis added.