An icicle clinging to grass on a grave is a small, almost accidental thing, and Shelley builds a whole argument around it. The frozen drop becomes a "pure gem," then a "dim icedrop," and finally, by implication, a teardrop caught and fixed by the cold. The central idea is that one sincere tear shed over a humble grave is worth more than all the glory won on battlefields.
The poem starts oddly for an elegy. Instead of describing the grave, the speaker gives orders. "Oh! take the pure gem," he says, first to a place where "southerly breezes" blow and a faithful, loving heart might melt it and let it rise "to gleam in the skies," then to the battlefield, where a warrior or tyrant-slayer "plants Liberty's flag." Only in the third stanza do we learn why he cares: "For I found the pure gem" at daybreak on a "snow-covered plain." Holding back this explanation means we meet the icicle first as a treasure and only later as a sign of loss. A contrast of temperature runs underneath. Love's "warm current" that "never freezes" is set against the frost on the grave, so warmth stands for feeling and cold for death.
The middle stanzas try to console, though not very convincingly. "Regret is an insult—to grieve is in vain," the speaker insists, because the dead person's "spirit so fair" has gone to join "its own kindred" in Heaven. Yet the next stanza undermines this by imagining a "Spirit of kindness descending" to weep over the "lowly-built sepulchre," and then draws a neat piece of logic: "if ANGELS can weep, sure MAN may repine." The capitals on THEE, ANGELS and MAN make the line sound like a voice pressing its point. The icicle becomes heaven's own tear, which gives human grief permission. The poem never says who lies in the grave. We learn only that the person was "fair" and "sincere," and that the grave is "lowly" and "low-laid," a modest resting place set against all the grand talk of flags and fame.
The form is steady. Every stanza has seven lines rhyming ABABBCC, so each ends with a couplet that clicks shut: "arise/skies," "free/thee," "repine/shrine," "tear/sincere." The rhythm is mostly anapaestic, two light syllables then a beat, in lines of about four stresses: "Oh! take the pure gem to where southerly breezes." Feminine endings like "breezes/freezes" and "defending/bending" add a swaying, song-like lilt. That lilt suits the tender passages, but it sits strangely beside the violence of the battle scenes, as if a lullaby were being sung over a war.
The final stanza is the most revealing. By rhyming "glory" with "gory," Shelley makes the two words collapse into one another. The "altar of glory" is stained by "millions of blood-reeking victims," and the widow's tears and the pining orphans are the price. "Reeking" has already appeared in "guilt-reeking gore" in stanza two, so the earlier picture of the freedom-fighter is tarnished after the fact. That earlier stanza praised the patriot, but its language was already uneasy, with its "fell corpse" and its blood. By the end the speaker renounces Fame altogether: "all thy glories I'd yield for a tear." The last word, "tear," matches the "teardrop" of stanza four, and we realise the icicle has been one all along.
The diction ("bosom," "repine," "sepulchre") belongs to a conventional sentimental elegy, and this is far from the best-known Shelley. It still repays attention. Readers who know him as a political radical will recognise the concern with tyranny, liberty and the human cost of violence. Here those public themes are measured against a private moment, one frozen drop on a patch of grass, and private feeling wins.