3 Away with the reasons of philosophers, who assert that a wise man is not affected by mental perturbations. God has made foolish the wisdom of this world; and the Lord knows the thoughts of men, that they are vain. It is plain that the mind of the Christian may be troubled, not by misery, but by pity: he may fear lest men should be lost to Christ; he may sorrow when one is being lost; he may have ardent desire to gain men to Christ; he may be filled with joy when such is being done; he may have fear of falling away himself from Christ; he may sorrow over his own estrangement from Christ; he may be earnestly desirous of reigning with Christ, and he may be rejoicing in the hope that such fellowship with Christ will yet be his lot.
These are certainly four of what they call perturbations— fear and sorrow, love and gladness. And Christian minds may have sufficient cause to feel them, and evidence their dissent from the error of Stoic philosophers, and all resembling them: who indeed, just as they esteem truth to be vanity, regard also insensibility as soundness; not knowing that a man's mind, like the limbs of his body, is only the more hopelessly diseased when it has lost even the feeling of pain.
Source: Tractates on the Gospel of John (New Advent)