La quinta fonte è del color de l'herba,
Ma pur di gemme ella riluce e d'oro;
E di quanti metalli in sen riserba
L'antica madre abonda il bel tesoro:
E con fiorita vista, e con superba,
Frondeggia intorno a lei palma et alloro,
E coronata di sue verdi selve,
Nel grembo accoglie armenti e greggie e belve.
The fifth spring has the color of grass
While shining with gems and with gold;
As many metals as Mother Earth keeps
In her womb make its rich treasure.
In their flowery and superb appearance
There grow palms and laurels all about;
Crowned with its green forests, the spring
Hosts herds and flocks and wild beasts.
Now, the fifth and last river symbolizes dry land! On the other hand, both Genesis and the Theory of Evolution (that is a masked version of the Bible, as some authors stress) see life on dry land as a "con-sequence" of sea life.
In brief, Tasso's Metaphysics of Water has started from the universe's borders "and beyond," and gradually gone down to life on Earth. Such emanative pattern is based on the Biblical account of creation only in part, it obviously draws on Neo-Platonic sources as well.
This mix or compromise between traditional Christian tenets and Neo-Platonic philosophy is 'officially' stated by Tasso in the dedication of his prose dialogue Il Messaggero ("The Messenger," i.e. the spirit he said he often happened to talk to while in prison; see also Giacomo Leopardi's Dialogue between Torquato Tasso and His Home Genius, of which a complete English translation is provided here).
In the dialogue itself, Tasso shows this hypothesis concretely operating with reference to the origin and 'spiritual mechanism' of the universe, paving the way -- often in the very details -- to his own long poem Il Mondo Creato, that therefore was not only the outcome of his conversations with the learned mother of Count Giovanni Battista Manso (as it happened to be affirmed in this blog too. With apologies).