Again, in the Epistle to the Corinthians he says: “For my speech and my preaching was not in the enticing words of man's wisdom, but in demonstration of the Spirit and of power; that your faith should not stand in the wisdom of men, but in the power of God.” And again he says: “As it is written, Eye has not seen, nor ear heard, neither have entered into the heart of man, the things which God has prepared for them that love Him. But God has revealed them unto us by His Spirit: for the Spirit searches all things, yea, the deep things of God. For what man knows the things of a man, save the spirit of man which is in him? Even so the things of God knows no man, but the Spirit of God.” And again he says: “But the natural man receives not the things of the Spirit of God.”
Source: A Sectional Confession of Faith (New Advent)