Scripture is the Defining Revelation of God

It is important to understand in this discussion that Special Revelation in Scripture is the defining revelation of God. First of all, the fundamental purpose of Special Revelation right from the beginning has been to define and interpret both General Revelation and the things that are not seen, namely, the spiritual realities of God and creation as the foundation for the material realities found in General Revelation. God's spoken word functions specifically as an interpretation of reality for mankind. Second, the very nature of General Revelation is that it needs to be processed and interpreted in the mind of man. Every fact, event or thing can and does receive different interpretations from different persons. Even before the Fall, Adam and Eve were able to consider a completely different interpretation of what eating of the forbidden tree would mean for them. With respect to General Revelation, the human interpretation of it determines what is heard and seen by the observer. With Special Revelation there is a different process; Scripture itself is its own interpreter. Not only do the words of Scripture communicate spiritual thoughts and concepts directly to the human mind (try for example to draw a picture or imagine a reality that communicates what these simple words do, "the heavens declare the glory of God"), but those words of Scripture which are more difficult to understand are made clear by words found elsewhere in Scripture. The four perfections of Scripture mentioned above, and built into it by its very inspiration as God's word, certify to mankind that it does not have to look elsewhere for a perfect interpretation of reality. In fact, because of the Necessity, Authority, Perspicuity and Sufficiency of Scripture, it is a sin to look elsewhere for an interpretation of reality, especially into General Revelation itself as is common among unbelieving philosophies.

—Robert Grossman, 'What We Think Before We Think: A Presuppositional Apologetics Primer,'pg. 38–39