The weak eye of the human mind is not fixed on that excellent light unless purified by the justice of faith.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic justice faith
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17611/pg17611-images.html

Context

“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."” source