would not, from all the borders of itself, burst like a star: for here there is no place that does not see you. You must change your life.
To pick up with this enjambment from stanza 3: without the inner light, the statue would not be able to "burst like a star."
Where we just said "untamable," we could have also said, "uncontainable." According to the speaker's simile, the statue's inner light can't be held in by its physical form; here, the spirit of the statue seems to overflow its body and radiate out into the world.
In fact, the statue's energy seems to permeate the whole world now: it's escaped the fragile shell of its body, and it suffuses everything around it with a kind of consciousness. It may seem a bit creepy that "here there is no place / that does not see you," but it's also inspiring. The spirit of art seems to be everywhere, and it means that any one of us can be creators, as well as observers.
This also reminds us of the statue's powerful gaze. It may not be literally looking at us, but figuratively this magnificent work is locking eyes with us, commanding our attention.
This last feeling of magical fusion between spectator and work of art is what leads the speaker to declare, both to himself and to us, that "You must change your life." When confronted by a work of such overwhelming beauty, we have no choice. You—we, that is—must examine ourselves and decide what we can offer to the world.