Commentators on Scripture during the medieval era developed a complex means of interpreting the Bible known as the quadriga. According to the medieval quadriga, every biblical passage had a fourfold meaning—a literal sense, a moral sense, an allegorical sense, and an anagogical sense. To know the literal or most obvious meaning of a passage was a good thing, but to know the higher moral, allegorical, and anagogical meanings was even better. Precious few, however, could attain to these other, more hidden meanings of Scripture. This tended to obscure the meaning and significance of the Bible for the uneducated, and it led to all sorts of fanciful interpretations among those who had more learning. Only the most “advanced” thinkers, for example, could see that the census recorded in Numbers was not really about the number of Israelite soldiers but rather the several steps it takes for the soul to ascend to God.
Of course, there is nothing in Scripture itself that justifies such a view of biblical interpretation. In fact, if the Bible teaches anything about itself, it is that its basic message is clear enough for anyone—even a child—to understand. This idea is known as the clarity of Scripture, which is also called the perspicuity of Scripture. It was a doctrine that the Protestant Reformers embraced, and they endeavored to return the church to the clearest, literal meaning of the Bible.
That the Bible is clear enough for even a child to understand is assumed in passages such as Deuteronomy 6:6–9. Moses instructs the people of Israel to teach the divinely revealed commandments of God to their children. This implies that the children are capable of understanding and applying the Word of God as their parents teach it to them. But note that it also implies that ordinary mothers and fathers are able to have a grasp of Scripture sufficient enough to teach it to their children. This is particularly notable, given that most of the people to whom Moses originally spoke these words would not have had much in the way of education, and many of them would have been unable to read at all. Neither of these factors, however, was a barrier to understanding enough about the Scriptures to be able to understand them and teach them to others.
The clarity of Scripture does not deny that some passages of Scripture are difficult to understand (2 Peter 3:15–16). It does mean that anyone who studies the Word of God can discern the basic message of salvation and what it means to please the Lord.