Four short lines, no punctuation, and a whole small drama of morning-after attention. The title sets the scene: dregs are what is left at the bottom of a glass once the good part is gone. The speaker looks into that leftover liquid and finds a mite, a speck of life so small that it needs a comparison to be seen at all. The poem's central idea is that even the residue of an evening, the unappealing bit nobody wants, can hold something exact and strangely admirable. It also asks what happens when a loose, light-headed mood meets a sudden, precise detail.
The first couplet is a small puzzle. "yesterday my head / was lighter than my glass" turns the usual logic upside down. We expect a glass to be emptied and made light, while a head grows heavy. Here the head is the lighter vessel, which can be read as giddy, tipsy, or simply empty of thought. Head and glass are set side by side as two containers, each holding something that has since drained away. The word "yesterday" matters too. Judging by it, the glass has stood around since then, so the speaker is looking at a stale remainder, and the light-headedness is already a memory. The poem begins by weighing two things against each other and ends by finding something that weighs almost nothing.
The second couplet changes pace with "discover," a verb that belongs more to explorers and scientists than to someone picking up an old glass. "Mite" does a lot of work for so small a word. It names a tiny creature, but it also means a very small amount, and it sounds like "might." A mite in a drink is normally a reason for disgust, yet the poem refuses that reaction and calls the creature "perfect." The simile that follows is the surprise: "perfect as an angry letter." The comparison can be read in two ways. A dark speck against the liquid looks like a written mark, a letter of the alphabet. And an angry letter, once written, is a finished thing, compact, pointed, with nothing wasted. The mite is complete in the same way, small and sharp and entirely itself. There is also a dry humour in the pairing. The mite is silent and indifferent, while the letter is full of heat, and the gap between them makes the line memorable.
The sound of the poem supports this. By my count the lines run five, six, eight and eight syllables, so the poem opens out as the discovery arrives, as if the speaker's attention is widening just as the object shrinks. There is no rhyme, and the lowercase, unpunctuated lines read like a thought spoken aloud. The sound patterns are quieter. The long "i" runs through "lighter," "which," "I" and "mite," so the weightless head of the first couplet is echoed in the nearly weightless creature of the second. "Lighter" and "mite" are close cousins in sound, which quietly links the two images. The final line leans on clipped consonants, "perfect," "letter," with their hard p and t, like a pen striking the page. The last word is a falling two-syllable ending, so the line trails off rather than slamming shut, and the "angry letter" ends up sounding strangely gentle.
The title closes the loop. "Dregs" describes the contents of the glass, but it could describe the poem as well: what is left once everything inessential has been poured away. Very little remains, yet nothing in it feels careless.
What makes the poem worth reading is how much it does with so little. It does not explain the drinking, the mood, or the anger behind the letter, and it leaves the reader to fill those gaps. In four lines it manages to be funny, slightly unsettling, and oddly tender toward a creature most people would tip down the sink. It suggests that attention is a form of generosity, and that a patient look at the least promising thing in the room can turn up a surprise.