Start not -- nor deem my spirit fled;
In me behold the only skull
From which, unlike a living head,
Whatever flows is never dull.
I lived, I loved, I quaffed, like thee:
The reader grasps that it is the skull,  anthropomorphised  to imitate a human, that is speaking.  It is astonishing, so the ‘Start not’ that begins the poem is understandable.
Lines Inscribed Upon a Cup Formed from a Skull