he has to cross his
sword in deadly duel with this lady. Malign stars rule the hour: he
knows not who she is: misadventure makes her, instead of him, the victim
of their encounter. With her last breath she demands baptism--the good
Tasso, so it seems, could not send so fair a creature of his fancy as
Clorinda to the shades without viaticum; and his poetry rises to the
sublime of pathos in this stanza:

Amico, hai vinto: io ti perdon: perdona
Tu ancora: al corpo no, che nulla pave;
All'alma si: deh! per lei prega; e dona
Battesmo a me ch'ogni mia colpa lave.
In queste voci languide risuona
Un non so che di flebile e soave
Ch'al cor gli serpe, ed ogni sdegno ammorza,
E gli occhi a lagrimar gl'invoglia e sforza (xii. 66).

Here the vague emotion, the _non so che_, distils itself through
Clorinda's voice into Tancredi's being. Afterwards it thrills there like
moaning winds in an Aeolian lyre, reducing him to despair upon his bed
of sickness, and reasserting its lyrical charm in the vision which he
has of Clorinda among the trees of the enchanted forest. He stands
before the cypress where the soul of his dead lady seems to his
misguided fancy prisoned; and the branches murmur in his ears:

Fremere intanto udia continuo il vento
Tra le frondi del bosco e tra i virgulti,
E trarne un suon che flebile concento
Par d'umani sospiri e di singulti;
E un non so che confuso instilla al core
Di pieta, di spavento e di dolore (xiii. 40).

The master word, the magic word of Tasso's sentiment, is uttered at this
moment of illusion. The poet has no key to mysteries locked up within
the human breast more powerful than this indefinite _un non so che_.

Enough has been said to show how Tasso used the potent spell of
vagueness, when he found himself in front of supreme situations. This
is in truth the secret of his mastery over sentiment, the spell whereby
he brings nature and night, the immense solitudes of deserts, the
darkness of forests, the wailings of the winds and the plangent litanies
of sea-waves into accord with overstrained humanity. It was a great
discovery; by right of it Tasso proved himself the poet of the coming
age.

When the _Gerusalemme_ was completed, Tasso had done his best work as a
poet. The misfortunes which began to gather round him in his
thirty-first year, made him well-nigh indifferent to the fate of the
poem which had drained his life-force, and