My good friend, you are a citizen of Athens, a city which is very great and very famous for its wisdom and power - are you not ashamed of caring so much for the making of money and for fame and prestige, when you neither think nor care about wisdom and truth and the improvement of your soul?
'Thou shalt not kill' does not apply to murder of one's own kind only, but to all living beings and this commandment was inscribed in the human breast long before it was proclaimed from Sinai.
cruelty to animals is contrary to man's duty to himself, because it deadens in him the feeling of sympathy for their sufferings, and thus a natural tendency that is very useful to morality in relation to other human beings is weakened.