far removed from the primitive and simple exercise of his psychical
life, that he finds it difficult to picture to himself the ancient and
spontaneous conditions under which his senses communicated with the
world and with himself. And therefore, without further consideration, he
thinks and believes that in primeval times everything took place in the
same way as it does at present, and, which is a still greater error, as
it takes place in the lower animals.

This identification of the complex machinery of human perception with
that of animals must not be regarded as an absurd paradox, since, as we
have shown in an earlier work, they were originally and in themselves
the same.[8] By pursuing an easy mode of observation, divested of
prejudice, we may revert to that primeval state of human nature, and may
also comprehend with truth and certainty the condition of animals. For
the animal nature has not ceased to exist in man, and it may be
discerned by those who care to look for it; and careful study, with the
constant aid of observation and experiment, will reveal to us the hidden
life of sensation and intelligence in the lower animals.

There is a continual self-consciousness in all animals; it is
inseparable from all their internal and external acts, from every fact,
passion, and emotion; and this is clear and obvious. This fundamental
and persistent self-consciousness--persistent in dreams, and even in the
calmest sleep, which is always accompanied by a vague sensation--is the
consciousness of a living subject, active, impressionable, exercising
his will, capable of emotions and passions. It is not the consciousness
of an inert thing, passive, dead, or extrinsic; for animal life consists
in sensation of greater or less intensity, but always of sensation.
Consequently, such a consciousness signifies for the animal a constant
apprehension of an active faculty exercised intrinsically in himself,