quiddity

To his followers, Keats is a poet’s poet, is the poet’s poet, a writer whose brief span compressed all the love, pain, and existential uncertainty of a lifetime, which the finest of his fifty-four published poems animate. He believed pain and trouble were their own education, “school[ing] an intelligence to make it a soul.” His was a rare gift, and yet his best poems weren’t earned without effort; early examples are uneven and clumsy, and for that perseverance and learning by shrewd emulation, we admire him all the more. His death at twenty-five trapped that quiddity in amber.
a root-cognate for “quidditch”?
quid·di·ty
/ˈkwidədē/
PHILOSOPHY
  1. the inherent nature or essence of someone or something.
    • a distinctive feature; a peculiarity.
      plural noun: quiddities
      “his quirks and quiddities”