The mountains and the hills... — Cheyne aptly compares —
“Ipsi lætitia voces ad sidera jactant
Intonsi montes.” VIRG., Æclog.
(The very hills, no more despoiled of trees,
Shall to the stars break forth in minstrelsies.)
The waving of the branches of the trees is, in the poet’s thoughts, what the clapping of hands is with men, a sign of jubilant exultation (Psalms 96:12).