In Vergilium Commentarius
Maurus (Marius) Servius Honoratus
STAGNIS QUAE FLUMINIBUSQUE SONORIS PRAESIDET Iuturna fons est in Italia saluberrimus iuxta Numicum fluvium, cui nomen a iuvando est inditum. Cum enim naturaliter omnis aqua noxia sit extraneorum corporibus, hic omnibus saluberrimus fons est. De hoc autem fonte Romam ad omnia sacrificia aqua adferri consueverat. Bene ergo Vergilius Turno fingit sororem, quae laborantes iuvare consuevit. Huic fonti propter aquarum inopiam sacrificari solet: cui Lutatius Catulus primus templum in campo Martis fecit; nam et Iuturnas ferias celebrant qui artificium aqua exercent, quem diem festum Iuturnalia dicunt. Varro rerum divinarum quarto decimo ait Iuturna inter proprios deos nymphasque ponitur.
Who/which protects the pools and sounding rivers: Iuturna is a very health-giving spring in Italy near the river Numicus, whose name was given it for its helpfulness. For although naturally every spring might be harmful to the bodies of foreigners, this spring is very healthful for all. Moreover, it was the custom that from this fountain water was brought to Rome for all sacrifices. Therefore, Vergil rightly imagines the sister of Turnus, who was accustomed to help those working. It is customary to make sacrifice to this spring on account of lack of water: for it Lutatius Catulus first built a temple in the Campus Martius; and those who practice a skill with water celebrate the holiday of Juturna; this festal day they call the Juturnalia. Varro, in book fourteen of the work on divine things, says that Juturna is regarded among the special gods and nymphs.
Translation by Jane W. Crawford, © 2001.