Animals live in the herd instinct. They do not possess self-consciousness as individualized human beings possess it, nor have they the capacity of aspiring to what is above their own level. But they are subject to evolution and will ultimately arrive at our level. Kindness to those nearest the human stage promotes their evolution into its best side. Cruelty to them launches them into its worst side and punishes us with a karma of criminal primitive classes of the lowest order.
-- Notebooks Category 5: The Body > Chapter 3: Diet > # 58