We cannot know his legendary head with eyes like ripening fruit (1-2)
The identity of the statue, though revealed in the title, is never fully knowable.
Otherwise the curved breast could not dazzle you so (4-5)
Okay, this seems a bit weird—all of a sudden, "you" are the speaker, or the speaker is addressing "you" or something. This shift in pronoun takes us directly into the experience of looking at the statue, and creates a momentary crisis of identity for the reader.
for here there is no place that does not see you. (12-13)
If the artwork (or the world, more broadly) can examine us, then we should probably examine ourselves, right? This suggests the need for introspection.
You must change your life. (14)
Any examination of one's identity—whether by someone else or by oneself—must lead to some impulse to change. This notion reminds us that identity is always in flux, rather than being predetermined. You must change your life—and you can change it, too.