The Trinity And The Waters

Dominus diluvium inhabitat, et sedebit Dominus rex in aeternum. Dominus virtutem populo suo dabit, et benedicet populum suum in pace. Decursis virtutibus Spiritus septiformis, in tertio ordine ad Trinitatis complexionem mirabili dispositione pervenit. Dicendo enim in his duobus versiculis tertio Dominus, ostendit sanctam Trinitatem diluvium, id est aquas baptismatis inhabitare; sicut in Evangelio dictum est: Euntes baptizate omnes gentes in nomine Patris, et Filii, et Spiritus sancti. Sed quaeramus cur hic diluvium pro sacris fontibus positum est? Merito, quoniam illud quod factum est sub Noe, baptismatis sacri gerebat imaginem. Nam sicut istud purgat animas sordibus peccatorum, ita et illud diluvium mundi crimina probrosa delevit. Merito ergo pro baptismate diluvium positum est, ad cuius similitudinem constat effectum. Nam quod tertio Dominus repetiit, sine distinctione personarum, licet intelligi primum dictum de Spiritu sancto, Dominus diluvium inhabitat. Sequitur, et sedebit Dominus Rex in aeternum; hoc autem de Filio recte intelligimus. Dominus virtutem populo suo dabit, de Patre competenter advertimus. Populo suo, significat Christiano, quem de sacri baptismatis munere conquisivit. Subiunxit etiam: Et benedicet populum suum in pace. Non dixit benedicent, sed benedicet, quia unus est Dominus Deus noster. In pace, propter illud Evangelii: Pacem meam do vobis, pacem meam relinquo vobis. Una est enim pax et Patris, et Filii, et Spiritus sancti. Cassiodorus, Expositio In Psalterium, Psalmus XXVIII Source: Migne PL 70.201d-202b

The Lord makes a dwelling place of the flood, and the Lord shall sit as king in eternity. The Lord shall give virtue to His people, and He shall bless His people with peace. 1 For the pouring forth of the virtues, the seven formed Spirit, third in the order of the complex of the Trinity, comes by a wondrous arrangement. For in speaking of the Lord three times in these two lines, he reveals the flood is the Holy Trinity, that is, that it dwells in the baptismal waters, like He said in the Gospel, 'Go and baptise all the nations in the name of the Father and the Son and the Holy Spirit.' 2 But shall we not ask why the flood is set down here for the holy waters? Rightly, because what was done with Noah bears the image of baptism. For as baptisms purge the souls of sinners of defilement, so even the flood removed shameful wickedness from the world. Rightly, then, is the flood set down for baptism, for they have a similarity of effect. And in his calling on the Lord three times, without distinction of person, one may understand the first to be be the Holy Spirit, 'The Lord makes a dwelling place of the flood.' And then what follows, 'The Lord shall sit as king in eternity,' we understand to about the Son.  And 'The Lord shall give virtue to His people,' aptly refers to the Father. 'To his people,' signifies Christians, whom He has sought out with the gift of holy baptism. After this it is written, 'And He shall bless His people in peace.' It does not say, 'They shall bless,' but 'He shall bless,' because the Lord our God is one. 'With peace,' according to the Gospel: 'My peace I give to you, my peace I leave to you.' 3 For the peace of the Father and the Son and the Holy Spirit is one. Cassiodorus, Commentary On The Psalms, from Psalm 28 1 Ps 28.10 2 Mt 28.10 3 Jn 14.27