I grieve for life's bright promise, just shown and then withdrawn.

The line expresses a grief that is not merely for loss itself but for the particular cruelty of loss that arrives at the moment of dawning hope. “Life’s bright promise” suggests youth, possibility, or an anticipated future; “just shown and then withdrawn” compresses the experience of sudden bereavement or disappointment into a single motion—revelation followed immediately by erasure. The emotional force lies in the contrast between brightness and withdrawal, implying that the speaker’s sorrow is sharpened by how briefly the promise was allowed to appear. In Bryant’s elegiac mode, such phrasing often frames mortality as a thief of potential as well as of presence.