What is this prejudice in favor of progress? The trouble with his mistress, Saper decided, was that she had too successfully specialized, was too purely a mistress, perfect but fragile, like a horse’s leg, which is really half foot, extended and whittled and tipped with one amazing toenail. The little Eohippus, in its forest of juicy soft leaves, scuttled like a raccoon; and even Mesohippus, though as big as a collie, kept three toes of each foot on the ground. Eohippus, it seemed to Sapers, was like a furtive little desire that evolves from the shadows of the heart into a great, clattering unmanageable activity.
– The Man Who Loved Extinct Mammals, John Updike.