The paintings by El Greco (1541-1614) always struck me as very original, ever since I glanced upon one in an art museum.
Giorgio Giulio Clovio was an artist freind of El Greco, although much older than him.
Clovio reports visiting El Greco on a summer's day while the artist was still in Rome. El Greco was sitting in a darkened room, because he found the darkness more conducive to thought than the light of the day, which disturbed his "inner light". (quoted from M. Acton, Learning to Look at Paintings, p.82)
The figures depicted in the El Greco paintings appear as if they are shining from within.
The inner light, when it comes from the painter, is the source for great originality.
In order to be unique you need to listen to your inner voice, rather than attend to what is being said and circulated around you.
A pursuer of inner light goes far, freed from the conventions of the day.
"The Opening of the Fifth Seal" by El Greco.