The speaker asserts that heard melodies are sweet, while unheard ones are sweeter, so asks the soft pipes to play on.  
An interpretation of this work asks if there is paradox in the phrase "cold pastoral" in the final stanza. The speaker is asking what leaf-fringed legend haunts the titular object's shape, eventually inquiring about the ones that are coming to be sacrificed.  Critics argue as to who speaks the final 13 lines, perspectives include the poet or the titular object.  That titular object is described as the foster child of silence and slow time in the first stanza, and the speaker describes various images on the titular object through the other stanzas.  The speaker asserts that heard melodies are sweet, while unheard ones are sweeter, so asks the soft pipes to play on.  FTP name this poem that claims "Ye know on earth and all ye need to know is that beauty truth and truth beauty", written by John Keats.
An interpretation of this work asks if there is paradox in the phrase "cold pastoral" in the final stanza.
{Ode} on a {Grecian Urn}