What metaphors are used in On the Threshold by Eugenio Montale?

The wind is a metaphor (a word or phrase used in place of another word or phrase, suggesting a likeness between the two) for a fresh wave of life, untainted by the past.

In Stanza II, the poet takes up the idea of the wind as a metaphor for creativity and life. The whirring sound the person in the garden is hearing is not "flight" (that is, not something in the orchard moving away) but something "stirring" from within the "eternal womb"—a breath of new life, unconnected to the dead web of the past.