Comments by St. Athanasius, the great 4th century teacher. Being one the great intellectual lights of his time, I like the way he appreciates the power of the Psalms to stir the emotions.
"But even so, the Book of Psalms thus has a certain grace of its own, and a distinctive exactitude of expression. For in addition to the other things in which is enjoys an affinity and fellowship with the other books, it posses, beyond that, this marvel of its own – namely, that it contains even the emotion of each soul, and it has the changes and rectifications of these delineated and regulated in itself.
[And] in the Book of Psalms, the one who hears, in addition to learning these things, also comprehends and is taught in it the emotions of the soul, and consequently on the basis of that which affects him and by which he is constrained, he also is enabled by this book to possess the image deriving from the words.
And it seems to me that these words become like a mirror to the person singing them, so that he might perceive himself and the emotions of his soul, and thus affected, he might recite them."