Spiritually, by the birds of the air are meant the Saints who are born again in the water of holy Baptism; [ed. note: Vid. the Breviary Hymn, Magnae Deus Potentiae] and by devotion raise themselves above the earth and seek the skies. The Apostles are said to be of more value than these, because they are the heads of the Saints.
By the lilies also may be understood the Saints, who without the toil of legal ceremonies pleased God by faith alone; of whom it is said, “My Beloved, who feedeth among the lilies.” [Cant 2:16] Holy Church also is understood by the lilies, because of the whiteness of its faith, and the odour of its good conversation, of which it is said in the same place, “As the lily among the thorns.”
By the grass are denoted the unbelievers, of whom it is said, “The grass hath dried up, and the flowers thereof faded.” [Isa 40:7]
By the oven eternal damnation; so that the sense be, If God bestows temporal goods on the unbelievers, how much more shall He bestow on you eternal goods!
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).