Did we think that the first symbolical river was hard to decipher? We hadn't seen the second one yet!
Ma nel secondo pur, qual cervo o damma
L'huom correrìa per ammorzar la sete;
Bench'egli tutto al novo dì s'infiamma
Co' rai che sembran quasi accese mete.
Il fonte è del color di fiamma viva,
In cui spiegan il crin varie comete;
E d'ardenti sembianze auree faville
Hor turbate vi scorgi, et hor tranquille.
But to the second river, deer or doe-like
Man would run to quench his thirst, (*)
Even though at sunrise it is set on fire
By rays that look like burning spires. (**)
The spring is in color of the living flame (***)
In which comets unfold their tails;
And in it you can see golden sparks
Now being unsettled, now resting quiet.
(*) The first two lines may suggest that the second river means divine grace, on the basis of the standard mystical interpretation of Psalm 42.
(**) "Spires": Tasso actually says mete referring to the shape of Latin metae, the turning points for horse races; more or less like little obelisks.
(***) Literal quotation from Dante, Purgatorio 30: 33. Beatrice is described there, who is the symbol of theology and/or grace and/or the Bible (in the Middle Ages the three concepts were much more interconnected than nowadays). This apparently strengthens the hypothesis that the river means grace, unfortunately the following lines makes things quite tangled again. The whole octave might also hint at the role of angels as the intermediaries of grace, partly busy in the world, partly worshiping God in heaven -- but all of this sounds quite 'stretched.'