We sacrifice other species to our own not because our own has any objective metaphysical privilege over others, but simply because it is ours. It may be very natural to have this loyalty to our own species, but let us hear no more from the naturalists about the "sentimentality" of anti-vivisectionists. If loyalty to our own species - preference for man simply because we are men - is not sentiment, then what is?
C.S. Lewis: essay collection and other short pieces (ed. Fount, 2000)