In this poem, the speaker evidently returns to the place where she last saw a loved one; perhaps this beloved person has died or is simply no longer in the speaker's life. Either way, this person's "absence" is clearly quite affecting for her, and she is conscious that, despite the natural beauty all around her in this place, it "seem[s] a savage force" that disrupts the gentleness of the garden setting.
There are several images. The "fountains [that] sprayed their usual steady jet" and "birds that shook out of the trees" are both visual images (descriptions of physical things that we can see in our mind's eye), and the "level breeze" could be considered a tactile image (describing a physical thing that we could imagine feeling with our sense of touch).
The poem makes use of apostrophe, as the speaker addresses someone who is absent or dead and does not respond. The speaker personifies the birds as "thoughtless" and as "singing an ecstasy" that she cannot share with them. The absence of the missing loved one is compared, via metaphor, to "an earthquake tremor" that is created by the speaker "thinking of [their] name." When she recalls that missing beloved, the gentleness around her seems to be shaken.
In terms of structure, the poem is stanzaic, with three stanzas of five lines each. The first stanza focuses on the speaker's reintroduction to the setting in which she last met with her beloved. The second stanza continues with the description of the place but also introduces the idea that this place could cause "pain" or "discord." The third stanza explains how the speaker's grief over her beloved's absence changes the beautiful natural setting for her; its apparent gentleness hides how "savage[ly]" it affects her.
The tone of the poem, which is how the author feels about the subject, is sympathetic and sad. The speaker is presented as intelligent and self-aware, and the author seems to encourage us to feel for her and pity her for her terrible sense of loss. The poem presents the theme that the absence of a loved one can change the way one perceives the world, altering beauty with pain.