iousness was
present in the world as far back as the Silurian epoch. But, if the
earliest animals were similar to our rhizopods and monads, there must
have been some time, between the much earlier epoch in which they
constituted the whole animal population and the Silurian, in which
feeling dawned, in consequence of the organism having reached the
stage of evolution on which it depends.

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