r.
Now an animal may be led to pursue that course of action which is most
beneficial to the species by suffering, such as pain, hunger, thirst,
and fear; or by pleasure, as in eating and drinking, and in the
propagation of the species, etc.; or by both means combined, as in the
search for food. But pain or suffering of any kind, if long continued,
causes depression and lessens the power of action, yet is well adapted
to make a creature guard itself against any great or sudden evil.
Pleasurable sensations, on the other hand, may be long continued without
any depressing effect; on the contrary, they stimulate the whole system
to increased action. Hence it has come to pass that most or all sentient
beings have been developed in such a manner, through natural selection,
that pleasurable sensations serve as their habitual guides. We see this
in the pleasure from exertion, even occasionally from great exertion of
the body or mind,--in the pleasure of our daily meals, and especially in
the pleasure derived from sociability, and from loving our families. The
sum of such pleasures as these, which are habitual or frequently
recurrent, give, as I can hardly doubt, to most sentient beings an
excess of happiness over misery, although many occasionally suffer much.
Such suffering is quite compatible with the belief in natural selection,
which is not perfect in its action, but tends only to render each
species as successful as possible in the battle for life with other
species, in wonderfully complex and changing circumstances.

That there is much suffering in the world, no one disputes. Some have
attempted to explain this with reference to man by imagining that it
serves for his moral improvement. But the number of men in the world is
as nothing compared with that of all other sentient beings, and they
often suffer greatly without any moral improvement. This very old
argument from the existence of suffering against the existence of an
intelligent First Cause seems to me a strong one; whereas, as just
remarked, the presence of much suffering agrees well with the view that
all organic beings have been developed through variation and natural
selection.

At the present day, the most usual argument for the existence of an
intelligent God is drawn from the deep inward conviction and feelings
which are experienced by most persons.

Formerly I was led by feelings such as those just referred to (although
I do not think that the religious s