(Psalm 1:3, Clementine Vulgate) Et erit tamquam lignum quod plantatum est secus decursus aquarum, quod fructum suum dabit in tempore suo: et folium ejus non defluet; et omnia quæcumque faciet prosperabuntur.
The Douay-Rheims translates this into English as, "And he shall be like a tree which is planted near the running waters . . ."
How should decursus be parsed in this verse?
According to Wiktionary, secus is a preposition taking an accusative, but decursus doesn't look like it is in accusative form to me. What am I missing?