St. Athanasius of Alexandria: The Scriptures and true knowledge

For the searching of the Scriptures and true knowledge of them, an honourable life is needed, and a pure soul, and that virtue which is according to Christ; so that the intellect guiding its path by it, may be able to attain what it desires, and to comprehend it, in so far as it is accessible to human nature to learn concerning the Word of God. For without a pure mind and a modelling of the life after the saints, a man could not possibly comprehend the words of the saints. 

For just as, if a man wished to see the light of the sun, he would at any rate wipe and brighten his eye, purifying himself in some sort like what he desires, so that the eye, thus becoming light, may see the light of the sun; or as, if a man would see a city or country, he at any rate comes to the place to see it—thus he that would comprehend the mind of those who speak of God must needs begin by washing and cleansing his soul, by his manner of living, and approach the saints themselves by imitating their works; so that, associated with them in the conduct of a common life, he may understand also what has been revealed to them by God, and thenceforth, as closely knit to them, may escape the peril of the sinners and their fire at the Day of Judgment, and receive what is laid up for the saints in the Kingdom of Heaven, which eye has not seen, nor ear heard, neither have entered into the heart of man,whatsoever things are prepared for them that live a virtuous life (1 Cor. 2:9), and love the God and Father, in Christ Jesus our Lord: through Whom and with Whom be to the Father Himself, with the Son Himself, in the Holy Spirit, honour and might and glory for ever and ever. Amen. 

(On the Incarnation of the Word, 57)