How does the rhyme scheme in “Ode on a Grecian Urn" contribute to its meaning?

As in other odes, the two-part rhyme scheme (the first part made of ab rhymes, the second of cde rhymes) creates the sense of a two-part thematic structure as well. The first four lines of each stanza broadly set out the subject of the stanza, and the last six generally explain or develop it.