A Tree of Wisdom

Et erit tamquam lignum quod plantatum est secundum decursus aquarum  Id est, aut secundum ipsam Sapientiam, quae dignata est hominem suscipere ad salutem nostram; ut ipse homo sit lignum plantatum secundum decursus aquarum: potest enim et hoc intellectu accipi, quod in alio psalmo dicitur: Fluvius Dei repletus est aqua. Aut secundum Spiritum Sanctum, secundum quem dicitur: Ipse vos baptizabit in Spiritu Sancto; et illud: Qui sitit, veniat, et bibat; et illud: Si scires donum Dei, et quis est qui a te aquam petit; petisses ab eo, et daret tibi aquam vivam, unde qui biberit non sitiet in aeternum; sed efficietur in eo fons aquae salientis in vitam aeternam. Aut secundum decursus aquarum, secundum populorum peccata, quia et aquae populi interpretantur in Apocalypsi; et decursus non absurde intellegitur lapsus, quod pertinet ad delictum. Lignum ergo illud, id est Dominus noster, de aquis decurrentibus, id est populis peccatoribus, trahens eos in via in radices disciplinae suae, fructum dabit, hoc est, constituet Ecclesias; in tempore suo, id est, postquam clarificatus est resurrectione et ascensione in coelum. Tunc enim Spiritu sancto misso Apostolis, et eis in fiducia sui confirmatis et directis in populos, fructificavit Ecclesias.  Sanctus Augustinus Hipponensi, Enarratio in Psalmum I

'And he shall be like a tree planted beside flowing waters'1  That is, either Wisdom itself, which  assumed man's nature for our salvation, that as man He might be 'the tree planted by flowing waters', for in this sense it can also be understood which is said in another Psalm, 'The river of God is full of water,'2 or the Holy Spirit, of whom it is said, 'He shall baptize you in the Holy Spirit,'3 and again, 'If any man thirst, let him come to me and drink,' 4 and again, 'If you knew the gift of God, and who it is that asks water of you, you would have asked of Him and He would have given you living water, of which whoever drinks shall not thirst in eternity, but in him it shall be made a well of water springing up to everlasting life.'5 Or, ' the flowing waters' may be the sins of the people, because first the waters are called peoples in the Apocalypse,6  and by 'flowing waters' is not unreasonably understood 'fall,' which pertains to sin. That tree then, that is, our Lord, from the running streams of water, that is, from a sinful people, drawing them into the roots of His discipline, will 'bring forth fruit,' that is, will establish Churches; 'in His season,' that is, after He has been glorified by His Resurrection and Ascension into heaven. For then, by the sending of the Holy Spirit to the Apostles, and by the confirmation of their faith in Him and command to go to the peoples, He made the Churches bring forth fruit. Saint Augustine of Hippo, Commentary on Psalm 1 1 Ps 1.3 2 Ps 64.10 3 Mt 3.11  4 Jn 7.37  5 Jn 4.10, 13 -14  6 Rev 17.15  7 Is 40:6-8