To the Hebrew decalogue and the Christian beatitudes must be added the first of Buddha's ten commandments: Kill not for Pity's sake, nor dare to slay… - Edward Payson Evans

In the higher organisms the higher faculties predominate, and in the lower organisms the lower faculties: but in all of them, from the highest to the lowest, the action is the resultant of impulses of sensation, perception, conception, and thought variously combined and inextricably blended.

The ethical corollaries to Darwin's doctrine of the origin of species and to his theory of development through descent under the modifying influences of environment and natural selection have already passed these bounds of beneficence not only by demanding the mitigation of cruelty to slaves, but also by the abolition of slavery, and not only by inculcating the kind treatment of animals by individuals, but also by asserting the principle of animals' rights and the necessity of vindicating them by imposing judicial punishments for their violation.

It is through the portal of spiritual kinship, erected by modern evolutional science, that beasts and birds [...] enter into the temple of justice and enjoy the privilege of sanctuary against the wanton or unwitting cruelty hitherto authorized by the assumptions and usurpations of man.