Mutability

Complimenting the theme of Change and Human Nature is the theme of Vulnerability and Threats. What makes humans mutable is their receptivity to constant streams of various thoughts and feelings. They're in a powerless position. They lack the strength to maintain a thought or feeling for an extended time.

Yet, in Stanza 1, the speaker briefly presents humans as threats when the speaker compares them to clouds. The humans/clouds come across as dangerous and uncontrollable as “they speed and gleam and quiver, / Streaking the darkness radiantly!” (Lines 2-3). The speaker creates a dangerous, devil-may-care image of humans. They use specific language to convey their chaotic, transgressive qualities. Ultimately, the human threat is extinguished by “Night,” which “closes round” the humans until they’re “lost for ever” (Line 4). Propulsive humans turn out to be vulnerable. Predatory night has no trouble making them/the clouds disappear. The night becomes the true threat, and humans have no effective defense against it.

The second simile supports the theme of vulnerability and threats. The speaker compares humans to “forgotten lyres” (Line 5), which puts humans in a weak position because they’re a thing of the past. If someone forgets something, it probably isn’t significant. Conversely, the lyre still manages to serve as a threat as its “dissonant” (Line 5). The musical instrument doesn’t produce a peaceful melody but a harsh sound, and “each varying blast” (Line 6) alludes to the violence of the instrument, with “blast” suggesting a gun blast or a bomb blast. As with the clouds, the lyre is ultimately vulnerable. Its unpredictability is due to its “frail frame” (Line 7). It lacks the strength to achieve a constant “mood or modulation” (Line 8), so it can’t be a consequential threat.

Humans are directly vulnerable in Line 9 as a “dream has power to poison sleep.” Awake and conscious, they’re under threat because “one wandering thought pollutes the day” (Line 10). Humans lack a strong defense system. They are invariably under attack and subject to factors beyond their control. Whatever they’re doing or feeling, it won’t last long. Their precarious predicament allows for “departure” (Line 14) at any moment—thoughts and feelings can come and go as they please. No human is immune from the overriding threat of change, which is why “[n]ought may endure but Mutability” (Line 16).