7 Therefore, brethren, may this be the result of my admonition, that you understand that in raising your hearts to the Scriptures (when the gospel was sounding forth, “In the beginning was the Word, and the Word was with God, and the Word was God,” and the rest that was read), you were lifting your eyes to the mountains. For unless the mountains said these things, you would not find out how to think of them at all. Therefore from the mountains came your help, that you even heard of these things; but you cannot yet understand what you have heard.
Call for help from the Lord, who made heaven and earth; for the mountains were enabled only so to speak as not of themselves to illuminate, because they themselves are also illuminated by hearing. Thence John, who said these things, received them— he who lay on the Lord's breast, and from the Lord's breast drank in what he might give us to drink. But he gave us words to drink. You ought then to receive understanding from the source from which he drank who gave you to drink; so that you may lift up your eyes to the mountains from whence shall come your aid, so that from thence you may receive, as it were, the cup, that is, the word, given you to drink; and yet, since your help is from the Lord, who made heaven and earth, you may fill your breast from the source from which he filled his; whence you said, “My help is from the Lord, who made heaven and earth:” let him, then, fill who can.
Brethren, this is what I have said: Let each one lift up his heart in the manner that seems fitting, and receive what is spoken. But perhaps you will say that I am more present to you than God. Far be such a thought from you! He is much more present to you; for I appear to your eyes, He presides over your consciences. Give me then your ears, Him your hearts, that you may fill both. Behold, your eyes, and those your bodily senses, you lift up to us; and yet not to us, for we are not of those mountains, but to the gospel itself, to the evangelist himself: your hearts, however, to the Lord to be filled.
Moreover, let each one so lift up as to see what he lifts up, and whither. What do I mean by saying, “what he lifts up, and whither?” Let him see to it what sort of a heart he lifts up, because it is to the Lord he lifts it up, lest, encumbered by a load of fleshly pleasure, it fall ere ever it is raised. But does each one see that he bears a burden of flesh? Let him strive by continence to purify that which he may lift up to God. For “Blessed are the pure in heart, because they shall see God.”
Source: Tractates on the Gospel of John (New Advent)