human (especially merely human); or subject to death
You are going to be the happiest of mortals.
In short, Miss Cunegonde, I have had experience, I know the world; therefore I advise you to divert yourself, and prevail upon each passenger to tell his story; and if there be one of them all, that has not cursed his life many a time, that has not frequently looked upon himself as the unhappiest of mortals, I give you leave to throw me headforemost into the sea.
"Well," said Candide to Martin when they had taken their leave, "you will agree that this is the happiest of mortals, for he is above everything he possesses."
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Don’t expect perfection of a mere mortal.
In the story, he was neither a mortal nor a god. He was a demi-god.