Pelo que posso dizer, esta citação aparece no livro ( não minha imagem ):
De uma fonte , é oferecida a seguinte análise:
The title of this novel comes from the writings of St. Macrina (the Younger?), who describes the unicorn as a creature which can be tamed only of its own free will. Indeed, the main theme of the story is whether freedom is possible in structure--in what, to other people, is practically slavery. Can one be free even when most tightly and narrowly bound?
A mesma fonte revela também quem são os unicórnios:
The two "young unicorns" are Emily Gregory, a talented young pianist blinded in a mysterious accident, and Josiah "Dave" Davidson, a former hood who mistrusts open doors and yet has a collection of keys to every door in the city's huge Episcopalian cathedral. They are lucky to have a couple of "old unicorns"--the Dean of the cathedral and Emily's piano teacher--taking an interest in them.
Outra fonte que enfoca a vida do autor também vincula St. Macrina ao The Young Unicorns e oferece é a própria explicação.