What is the importance of the hills and valleys in the poem, Lycidas?

The hills and valleys in the poem are where the speaker retreats to sing his funeral song for his fellow shepherd Lycidas. This setting is a conventional one for pastoral poetry, in which shepherds often sing and dance in their natural surroundings while subtly discussing things like poetry, politics, and love. The natural setting provides the opportunity for Milton to showcase his knowledge of classical mythology, which often attaches certain gods and goddesses to different parts of nature.