Since the time of Augustine in the 4th century, Christian theologians have used the metaphor of “two books” to picture how God has revealed Himself to us. Augustine said it like this: “Listen to the book that is the divine page; look at the book that is the orb of the world.”
Much later in the Belgic Confession, there is a more dramatic formation of the word picture:
We know [God] by two means: First, by the creation, preservation, and government of the universe; which is before our eyes as a most elegant book, wherein all creatures, great and small, are as so many characters leading us to see clearly the invisible things of God, even His everlasting power and divinity, as the apostle Paul says (Rom. 1:20)—all which things are sufficient to convince men and leave them without excuse. Second, He makes Himself more clearly and fully known to us by His holy and divine Word, that is to say, as far as is necessary for us to know in this life, to His glory and our salvation.
What God discloses about Himself in the natural world, the book of His works, has traditionally been called His “general revelation.” The testimony of Himself received in an extraordinary way by chosen recipients through the inspiration of the Holy Spirit, the book of His words, is termed “special revelation.” The conclusion of this theological classification is that the natural world is as much God’s “book” as is the Bible—both books often having significantly different purposes. Yet the Bible itself declares that both types of revelation are undeniably of divine origin (Job 38–41; Ps. 19).
Regarding general revelation, the Belgic Confession makes reference to the conclusion of the apostle Paul, who wrote:
What may be known about God is plain to [people], because God has made it plain to them. For since the creation of the world God’s invisible qualities—His eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse (Rom. 1:19-20 NIV).
So according to Paul, people have no excuse for denying the existence of God because nature itself shouts, “God is!”
For years I used this passage as an argument for God’s existence. But I have to confess that for most of those years I did not really spend a great deal of time considering what there is in the natural world that has such profound spiritual implications. The wilderness, where one can most clearly read God’s second book, must somehow have spiritual values for those who earnestly seek Him.