5.  Consciousness has various forms, which may be manifested independently of one another.  The feelings of light and colour, of sound, of touch, though so often associated with those of pleasure and pain, are, by nature, as entirely independent of them as is thinking.  An animal devoid of the feelings of pleasure and of pain, may nevertheless exhibit all the effects of sensation and purposive action.  Therefore, it would be a justifiable hypothesis that, long after organic evolution had attained to consciousness, pleasure and pain were still absent.  Such a world would be without either happiness or misery; no act could be punished and none could be rewarded; and it could have no moral purpose.

6.  Suppose, for argument’s sake, that all mammals and birds are subjects of pleasure and pain.  Then we may be certain that these forms of consciousness were in existence at the beginning of the Mesozoic epoch.  From that time forth, pleasure has been distributed without reference to merit, and pain inflicted without reference to demerit, throughout all but a mere fraction of the higher animals.  Moreover, the amount and the severity of the pain, no less than the variety and acuteness of the pleasure, have increased with every advance in the scale of evolution.  As suffering came into the world, not in consequence of a fall, but of a rise, in the scale of being, so every further rise has brought more suffering.  As the evidence stands it would appear that the sort of brain which characterizes the highest mammals and which, so far as we know, is the indispensable condition of the highest sensibility, did not come into existence before the Tertiary epoch.  The primordial anthropoid was probably, in this respect, on much the same footing as his pithecoid kin.  Like them he stood upon his “natural rights,” gratified all his desires to the best of his ability, and was as incapable of either right or wrong doing as they.  It would be as absurd as in their case, to regard his pleasures, any more than theirs, as moral rewards, and his pains, any more than theirs, as moral punishments.

7.  From the remotest ages of which we have any cognizance, death has been the natural and, apparently, the necessary concomitant of life.  In our hypothetical world (3), inhabited by nothing but plants, death must have very early resulted from the struggle for existence:  many of the crowd must have jostled one another out of the conditions on which life depends.  The occurrence of death, as far back as we have any fossil record of life, however, needs not to be proved by such arguments; for, if there had been no death there would have been no fossil remains, such as the great majority of those we met with.  Not only was there death in the world, as far as the record of life takes us; but, ever since mammals and birds have been preyed upon by carnivorous animals, there has been painful death, inflicted by mechanisms specially adapted for inflicting it.