13 “Yea moreover,” says he, “the beasts of the field.” The addition of “moreover” is by no means idle. First, because by beasts of the plain may be understood both sheep and oxen: so that, if goats are the beasts of rocky and mountainous regions, sheep may be well taken to be the beasts of the field. Accordingly had it been written even thus, “all sheep and oxen and beasts of the field;” it might be reasonably asked what beasts of the plain meant, since even sheep and oxen could be taken as such.
But the addition of “moreover” besides, obliges us, beyond question, to recognise some difference or another. But under this word, “moreover,” not only “beasts of the field,” but also “birds of the air, and fish of the sea, which walk through the paths of the sea”, are to be taken in. What is then this distinction? Call to mind the “wine-presses,” holding husks and wine; and the threshing-floor, containing chaff and grain; and the nets, in which were enclosed good fish and bad; and the ark of Noah, in which were both unclean and clean animals: and you will see that the Churches for a while, now in this time, unto the last time of judgment, contain not only sheep and oxen, that is, holy laymen and holy ministers, but “moreover beasts of the field, birds of the air, and birds of the sea, that walk through the paths of the sea.”
For the beasts of the field were very fitly understood, as men rejoicing in the pleasure of the flesh where they mount up to nothing high, nothing laborious. For the field is also “the broad way, that leads to destruction:” and in a field is Abel slain. Wherefore there is cause to fear, lest one coming down from the mountains of God's righteousness (“for your righteousness,” he says, “is as the mountains of God”) making choice of the broad and easy paths of carnal pleasure, be slain by the devil.
See now too “the birds of heaven,” the proud, of whom it is said, “They have set their mouth against the heaven.” See how they are carried on high by the wind, “who say, We will magnify our tongue, our lips are our own, who is our Lord?” Behold too the fish of the sea, that is, the curious; who walk through the paths of the sea, that is, search in the deep after the temporal things of this world: which, like paths in the sea, vanish and perish, as quickly as the water comes together again after it has given room, in their passage, to ships, or to whatsoever walks or swims.
For he said not merely, who walk the paths of the sea; but “walk through,” he said; showing the very determined earnestness of those who seek after vain and fleeting things. Now these three kinds of vice, namely, the pleasure of the flesh, and pride, and curiosity, include all sins. And they appear to me to be enumerated by the Apostle John, when he says, “Love not the world; for all that is in the world is the lust of the flesh, and the lust of the eyes, and the pride of life.” For through the eyes especially prevails curiosity.
To what the rest indeed belong is clear. And that temptation of the Lord Man was threefold: by food, that is, by the lust of the flesh, where it is suggested, “command these stones that they be made bread:” by vain boasting, where, when stationed on a mountain, all the kingdoms of this earth are shown Him, and promised if He would worship: by curiosity, where, from the pinnacle of the temple, He is advised to cast Himself down, for the sake of trying whether He would be borne up by Angels. And accordingly after that the enemy could prevail with Him by none of these temptations, this is said of him, “When the devil had ended all his temptation.” With a reference then to the meaning of the wine-presses, not only the wine, but the husks too are put under His feet; to wit, not only sheep and oxen, that is, the holy souls of believers, either in the laity, or in the ministry; but moreover both beasts of pleasure, and birds of pride, and fish of curiosity.
All which classes of sinners we see mingled now in the Churches with the good and holy. May He work then in His Churches, and separate the wine from the husks: let us give heed, that we be wine, and sheep or oxen; not husks, or beasts of the field, or birds of heaven, or fish of the sea, which walk through the paths of the sea. Not that these names can be understood and explained in this way only, but the explanation of them must be according to the place where they are found.
For elsewhere they have other meanings. And this rule must be kept to in every allegory, that what is expressed by the similitude should be considered agreeably to the meaning of the particular place: for this is the manner of the Lord's and the Apostles' teaching. Let us repeat then the last verse, which is also put at the beginning of the Psalm, and let us praise God, saying, “O Lord our Lord, how wonderful is Your name in all the earth!” For fitly, after the matter of the discourse, is the return made to the heading, whither all that discourse must be referred.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)