“Beauty is truth, truth beauty,—that is all / Ye know on earth, and all ye need to know.”
— John Keats, Ode on a Grecian Urn (1820)
Context
The closing couplet of Keats's 1820 ode, in which the speaker has spent five stanzas addressing the figures painted on an ancient Greek urn — lovers frozen mid-chase, musicians whose songs are forever unheard, a sacrificial procession winding toward an altar it will never reach. The urn finally speaks back. In the 1820 Lamia volume, Keats put the doubled phrase in quotation marks, attributing it to the urn itself; whether the rest of the couplet belongs to the urn or to the human speaker has been disputed by editors ever since.
How the repetition works
Every other strict-form entry in this catalogue uses adjacent repetition to amplify a single direction of feeling — Lear's five "never"s pile denial, Tennyson's three "break"s pile waves, Macduff's three "horror"s pile shock. Keats's doubled "truth" does the opposite: it sits at the hinge of a chiasmus (A:B::B:A), so the same word does subject-then-predicate work as the line pivots through its own axis. Read once forward, the sentence asserts Beauty = truth; the second "truth" then becomes the subject of the implied second clause and the equation reads back the other way, making the figure the rhetorical proof that the identity it asserts is reflexive. It is the catalogue's first example of epizeuxis used not to intensify but to invert — repetition as a pivot in zero metrical time, the doubled word transacting two grammatical roles in succession.