Whether God Can Be Known in This Life by Natural Reason?
Objection 1: It seems that by natural reason we cannot know God in
this life. For Boethius says (De Consol. v) that "reason does not
grasp simple form." But God is a supremely simple form, as was shown
above (Q. 3, A. 7). Therefore natural reason cannot attain to know
Him.
Obj. 2: Further, the soul understands nothing by natural reason
without the use of the imagination. But we cannot have an imagination
of God, Who is incorporeal. Therefore we cannot know God by natural
knowledge.
Obj. 3: Further, the knowledge of natural reason belongs to both
good and evil, inasmuch as they have a common nature. But the
knowledge of God belongs only to the good; for Augustine says (De
Trin. i): "The weak eye of the human mind is not fixed on that
excellent light unless purified by the justice of faith." Therefore
God cannot be known by natural reason.
_On the contrary,_ It is written (Rom. 1:19), "That which is known of
God," namely, what can be known of God by natural reason, "is manifest
in them."
_I answer that,_ Our natural knowledge begins from sense. Hence our
natural knowledge can go as far as it can be led by sensible things.
But our mind cannot be led by sense so far as to see the essence of
God; because the sensible effects of God do not equal the power of God
as their cause. Hence from the knowledge of sensible things the whole
power of God cannot be known; nor therefore can His essence be seen.
But because they are His effects and depend on their cause, we can be
led from them so far as to know of God "whether He exists," and to
know of Him what must necessarily belong to Him, as the first cause of
all things, exceeding all things caused by Him.
Hence we know that His relationship with creatures so far as to be the
cause of them all; also that creatures differ from Him, inasmuch as He
is not in any way part of what is caused by Him; and that creatures
are not removed from Him by reason of any defect on His part, but
because He superexceeds them all.
Reply Obj. 1: Reason cannot reach up to simple form, so as to
know "what it is"; but it can know "whether it is."
Reply Obj. 2: God is known by natural knowledge through the
images of His effects.
Reply Obj. 3: As the knowledge of God's essence is by grace, it
belongs only to the good; but the knowledge of Him by natural reason
can belong to both good and bad; and hence Augustine says (Retract.
i), retracting what he had said before: "I do not approve what I said
in prayer, 'God who willest that only the pure should know truth.'
For it can be answered that many who are not pure can know many
truths," i.e. by natural reason.
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