Genius
Etymology
Latin "genius" was the attendant spirit accompanying a person through life, from "gignere," to beget; a place had its "genius loci," its resident spirit. Only much later did the word migrate to mean extraordinary talent. The same root gives "genial," "ingenious," "genie," and "genuine."
noun · /JEEN-yuss/
Originally the guardian spirit assigned to a person or place at birth; later, exceptional innate power of mind.
What it names
It preserves an older idea — that brilliance is a spirit that visits you — beneath the modern sense of a brilliant person.
Example
The Romans would say a poet had a genius, not that he was one — inspiration came from outside the self.
Related idea
The Roman cousin of the Greek daimon that underlies eudaimonia — a tutelary spirit, not yet a synonym for brilliance.