"Heard melodies are sweet, but those unheard are sweeter"

In "Ode on a Grecian Urn", the speaker is thoughtfully examining the pictures on the outside of an urn. He approaches each picture on this urn with deep thought and consideration. He marvels at the thought that these pictures are standing still in time. He even refers to the urn as a "historian" that can tell the stories of time. The speaker was clearly engulfed by the pictures and the story that they told--that they would forever tell.

The stanza that I found to be the most interesting throughout this poem was the stanza that told of the young man and his lover. "Heard melodies are sweet, but those unheard are sweeter; therefore, ye soft pipes, play on." My understanding of this line is that those melodies that we can hear in mortal time may be sweet, but those that are unheard, as in those taking place in the picture on the urn, are sweeter because they are immortal. This is a melody that can withstand time. He continues this stanza by saying that the boy should not grieve, his lover's beauty will withstand time. He also mentions that the two's love will last forever, unlike the love that the humans experience above. I found that these ideas that the speaker presented to be thought provoking. People long to experience love that can withstand time. Here, on this urn, the two will be experiencing this undying love, however, these two lovers will be unable to kiss or simply touch. Should this love, that in which is frozen forever in time, be something that is desired by those privileged enough to experience the touch of their love? Should the reader desire to be like those others on the urn? Frozen forever in time?