Finally we turn to the perspicuity of nature which corresponds to the perspicuity of Scripture. We have stressed the fact that God’s revelation in nature was from the outset of history meant to be taken conjointly with God’s supernatural communication. This might seem to indicate that natural revelation is not inherently perspicuous. Then too it has been pointed out that back of both kinds of revelation is the incomprehensible God. And this fact again might, on first glance, seem to militate strongly against the claim that nature clearly reveals God. Yet these very facts themselves are the best guarantee of the genuine perspicuity of natural revelation. The perspicuity of God’s revelation in nature depends for its very meaning upon the fact that it is an aspect of the total and totally voluntary revelation of a God who is self-contained. God’s incomprehensibility to man is due to the fact that he is exhaustively comprehensible to himself. God is light and in him is no darkness at all. As such he cannot deny himself. This God naturally has an all-comprehensive plan for the created universe. He has planned all the relationships between all the aspects of created being. He has planned the end from the beginning. All created reality therefore actually displays this plan. It is, in consequence, inherently rational.
It is quite true, of course, that created man is unable to penetrate to the very bottom of this inherently clear revelation. But this does not mean that on this account the revelation of God is not clear, even for him. Created man may see clearly what is revealed clearly even if he cannot see exhaustively. Man does not need to know exhaustively in order to know truly and certainly. When on the created level of existence man thinks God’s thoughts after him, that is, when man thinks in self-conscious submission to the voluntary revelation of the self-sufficient God, he has therewith the only possible ground of certainty for his knowledge. When man thinks thus he thinks as a covenant creature would wish to think. That is to say, man normally thinks in analogical fashion. He realizes that God’s thoughts are self-contained. He knows that his own interpretation of nature must therefore be a re-interpretation of what is already fully interpreted by God.
—Cornelius Van Til, Christian Apologetics. 2nd ed (Phillipsburg, NJ: The Presbyterian and Reformed Publishing Company, 2003), ch. 2, sect;5.