The Mountain
In this poem, the image of the mountain represents the sexual aspects of a relationship. The mountain is described in the following way: "See the mountains kiss high Heaven," with the word "kiss" suggesting a more sexual companionship than previous descriptions. Here, Shelley is suggesting that it is natural for companionships to be physical.
Spiritual connection
Shelley writes that "All things by a law divine/ In one spirit meet and mingle." The fact that all things in nature have a companion symbolizes the fact that all humans are destined to have a companion. The fact that their "spirit" will "meet and mingle" symbolizes the fact that companionship includes a spiritual connection.
Flowers
In the second stanza, the speaker uses flowers to describe how his love has been unrequited. He says that in nature "no sister-flower would be forgiven/ If it disdained its brother." He uses this image to symbolize the fact that his lover's rejection of him is unnatural. As such, in this poem, the flowers symbolize unrequited love.
Water
In this poem, Shelley describes various aspects of nature which include oceans, waves, fountains, and rivers. Water is significant in this poem, as it represents the forcefulness of human emotions. While emotions can be forceful like the flowing water of a fountain, they can also be mild and calm like a river.