The Tree Of Life

Et erit tanquam lignum quod plantatum est secus decursus aquarum, quod fructum suum dabit in tempore suo. Et folium ejus non defluet, et omnia quaecunque faciet, prosperabuntur. Quae ista beatitudo est, quae ligno arboris comparatur nisi intelligamus in paradiso, illo beatorum loco, lignum vitae in medio lignorum aliorum de terra productum? Inter multa enim ligna quae erant speciosa ad aspectum, et bona ad escam, etiam hoc lignum terra produxit, et in medio paradisi erat; ut caetera ligna ejus viriditate florerent. Quod esse hoc lignum dicimus, nisi per quod nobis salus venit? Et recte hoc terra produxit, qui eum Virgo generavit, quae erat terra secundum auctoris sententiam, quae in eum dictat, 'Terra es, et in terram ibis'  Pulchre quoque in medio legitur lignorum aliorum; qui erat in medio apostolorum discentium, vel quia in medio erat mentis et cordis, sicut ipse ait: 'Medius vestrum stat, quem vos nescitis. Et alibi ait: 'Ego autem in medio vestrum sum. Denique et de ipso Salomon dixit: Lignum vitae est omnibus percipientibus eam. Qui ergo beatus est, imitator erit Domini Jesu, qui est lignum vitae, lignum sapientiae, plantatum in utero Virginis, voluntate Patris: a quo in perpetuum mansurum plantatur, ut fructum daret in tempore suo. Non enim potuit arescere ista plantatio, quae habebat ubertatem in se manentem gratiae spiritalis. Denique plenus Spiritu sancto Jesus regressus est ab Jordane. Hi sunt decursus aquarum de quibus dicitur in Evangelio: Flumina de ventre ejus fluent aquae vivae. Hoc autem dicebat de spiritu quem incipiebant accipere qui credituri erant. Sanctus Ambrosius Mediolanensis, Enarrationes In XII Psalmos Davidicos, Enarratio in Psalmum I  Migne PL 14 940-41

'And he shall be as a tree planted by flowing waters, which gives its fruit in its time. And the leaf of it shall not pass away, and in all that he does he will prosper.' 1 What is this blessing, which is compared to to the wood of the tree, unless we understand that in paradise, that place of the blessed, in the midst of other trees, the tree of life is produced? Among many trees that are fair to see and good for eating, even this tree the land produces, and in the midst of paradise it was, that other trees by its viridity flourish. What shall we say of this wood unless that by it salvation comes to us? And rightly here the land produced this one whom the Virgin bore, she who is the land according to the understanding of the Creator, who said to him, 'You are earth and into earth you shall go.' 2 And rightly also in the midst of the other trees it is said to be, He who taught in the midst of the Apostles, or because He was in the midst of mind and heart, as He himself said, 'Among you stands Him whom you do not know.'  3 And elsewhere He says, 'In the midst of you I am.' 4 Then Solomon says of Him : 'A tree of life it is to everyone who grasps it.' 5 So he who is blessed, he shall be an imitator of our Lord Jesus, who is the tree of life, the tree of wisdom, planted in the womb of the Virgin by the will of the Father, which is planted to remain forever, and that gives its fruit in its own time. For he was not able to destroy this which has been planted which has in it the fruit of spiritual grace. 6 Then full of the Holy Spirit Jesus withdrew from the Jordan. These are the flowing waters of which it is said in the Gospel. 'Rivers of living water will flow from his bosom. This He spoke concerning the spirit which they would began to receive who believed in him.' 7 Saint Ambrose, Commentary on the Psalms, Psalm 1 1 Ps 1.3 2 Gen 3.19 3 Jn 1.26 4 Luc 22.27 5 Prov 3.18 6 cf Mt 15.13 7 Jn 7.38-39