Houyhnhnm

I retain in my Mind the Lectures and Example of my noble Maſter and the other illuſtrious Houyhnhnms of whom I had ſo long the Honour to be an humble Hearer.

Source: wiktionary

"The Squire says you know a good deal about horses, so I suppose you understand the Houyhnhnm language? I'm learning it, and it is very nice," laughed Miss Celia, as Chevalita gave a little whinny and snuffled her nose into Ben's pocket.

Source: wiktionary

”The moment he called me his ‘gentle and reasonable Houyhnhnm,’” an archivist notes, “I should have known that the man was deranged.”

Source: wiktionary

Certainly the philosopher was not a pessimistic luncheon companion. He […] loped off in the direction of the London Library, leaving me with an impression of twinkling eyes, laughter lines (he whinnies like a donnish Houyhnhnm), and a sensibility genuinely focused on what will happen in the next five minutes - or five years - albeit one steeped in knowledge of the past.

Source: wiktionary