4 Let us see what comes next: If I was not humble-minded but have lifted up my soul. What inconsistency on the Prophet's part! He does not lift up his heart: he does lift up his soul. He does not walk amid things great and wonderful that are above him; yet his thoughts are not mean. He is exalted in mind and cast down in heart. He is humble in his own affairs: but he is not humble in his thought. For his thought reaches to heaven, his soul is lifted up on high. But his heart, out of which proceed, according to the Gospel, evil thoughts, murders, adulteries, fornications, thefts, false witness, railings, is humble, pressed down beneath the gentle yoke of meekness. We must strike a middle course, then, between humility and exaltation, so that we may be humble in heart but lifted up in soul and thought.
Source: Homilies on the Psalms (New Advent)