morphine is derived from "Morpheus" the Greek god of dreams

The name Morpheus was coined by Ovid (in his Metamorphoses xi.635), where he is the god of dreams and the son of Somnus 'sleep'. The usual connection is that in dreams Morpheus can take an shape he wants to.

At pater et populo natorum mille suorum
excitat artificem simulatorumque figurae
Morphea: non illo quisquam sollertius alter
exprimitincessus vultumque sonumque loquendi.

But the father rouses Morpheus from the throng
of his thousand sons, a cunning imitator of the human form.
No other is more skillful than he in representing
the git, the features, and the speech of men.

[Translation Frank Justus Miller.]

Ceci n'est pas un seing.