“Whoever hears me assert that the grey cat playing just now in the yard is the same one that did jumps and tricks there five hundred years ago will think whatever he likes of me, but it is a stranger form of madness to imagine that the present-day cat is fundamentally an entirely different one.”

"A History of Eternity" in Selected Non-Fictions Vol. 1, (1999), edited by Eliot Weinberger
Context: I turn to the most promising example: the bird. The habit of flocking; smallness; similarity of traits; their ancient connection with the two twilights, the beginnings of days, and the endings; the fact of being more often heard than seen — all of this moves us to acknowledge the primacy of the species and the almost perfect nullity of individuals. Keats, entirely a stranger to error, could believe that the nightingale enchanting him was the same one Ruth heard amid the alien corn of Bethlehem in Judah; Stevenson posits a single bird that consumes the centuries: "the nightingale that devours time." Schopenhauer — impassioned, lucid Schopenhauer — provides a reason: the pure corporeal immediacy in which animals live, oblivious to death and memory. He then adds, not without a smile: Whoever hears me assert that the grey cat playing just now in the yard is the same one that did jumps and tricks there five hundred years ago will think whatever he likes of me, but it is a stranger form of madness to imagine that the present-day cat is fundamentally an entirely different one.