Excerpted from In Physicam Aristotelis 4.1.7 

That word, which is taken from Job 28, carefully considered, opens for us the way toward foreseeing the fourfold type of cause in the book of Sententiae, namely material, formal, efficient, and final. For in fact, material cause is suggested in the name of rivers, formal cause in the careful examining of profundity, final cause in the revelation of hidden things, and the efficient cause is indeed understood in the substitution of two words, namely scrutatus est (he scrutinized) and produxit in lucem (he brought forth into the light). Material cause is suggested by the name of rivers in the plural, not in the singular, so that not only the material of the whole book or the subject in general be touched upon, but also the material of particular books in specific. On account of noting this, that next to the fourfold property of a material river, the spiritual river is fourfold, concerning which, according to the fourfold difference there are four books of Sententiae. For in fact, I consider the material river as far as duration, and I find perpetuity. For just as Isidorus says: "A river is perpetual flow." I consider as much as to its extension, and I find spaciousness. For in this, a river is distinguished from a brook. I consider as much as to movement, and I find circulation. For so it is said in the first book of Ecclesiastes: They are turned back to the place whence rivers go out, etc. I consider the effect, and I find a thorough cleansing. For a river cleanses the earth, through which it runs, on account of the abundance of its waters, and so because it is not defiled. And since all the transferrers transfer according to some likeness, from this fourfold condition the metaphor is taken, [and] a fourfold river is found in spiritual matters, just as we can gather from Scripture.

Original Latin

Primo, propter perennitatem dicitur fluvius personarum emanatio, quoniam illa emanatio sola est sine principio, sine fine. De hoc fluvio Daniel septimo: Antiquus dierum sedit, et fluvius igneus rapidusque egrediebatur a facie eius. Antiquus iste dierum est Pater aeternus, cuius antiquitas est aeternitas. Iste antiquus sedit, quia non solum in eo est aeternitas, sed etiam immutabilitas. A facie illius antiqui egrediebatur fluvius igneus rapidusque, id est, de sublimitate divinitatis eius procedebat plenitudo amoris et plenitudo virtutis: plenitudo virtutis in Filio, ideo fluvius erat rapidus; plenitudo amoris in Spitiru sancto, et ideo fluvius erat igneus.

Hunc errorem ipse dixit et suggessit impiis Manichaeis, qui totam machinam visibilium a Deo malo esse conditam contendunt. Huius draconis maxillas Dominus infrenabit, quando ablata sibi potestate suggerendi falsa, ostendet, se esse huius fluvii conditorem; unde in eadem auctoritate sequitur: Scient omnes habitatores Aegypti, quoniam ego Dominus.

Nam sacramentalis gratia procedit a Deo tamquam ab auctore et efficiente, a Christo tanquam a mediatore et a promerente. Propter quod dicuntur omnia Sacramenta efficaciam habere a passione Christi; unde testatur Augustinus: 'De latere Christi dormientis fluxerunt Sacramenta, dum inde fluxit sanguis et aqua'.

Euphrates interpretatur frugifer, in quo significatur Sacramentorum dispensatio, quae non tantum animam purgant a culpa, sed etiam fecundant in gratia. Quod significatum est Apocalypsis ultimo, ubi dicitur, quod iuxta fluvium crystallinum erat lignum afferens fructum, cuius folia erant in medicinam.