igher orders the actions are partly automatic, partly conscious. And in
man they are almost wholly conscious.

Throughout, however, there must necessarily exist a certain
classification of things according to their properties--a classification
which is either organically registered in the system, as in the inferior
creation, or is formed by experience, as in ourselves. And it may be
further remarked, that the extent to which this classification is
carried, roughly indicates the height of intelligence--that while the
lowest organisms are able to do little more than discriminate organic
from inorganic matter; while the generality of animals carry their
classifications no further than to a limited number of plants or
creatures serving for food, a limited number of beasts of prey, and a
limited number of places and materials; the most degraded of the human
race possess a knowledge of the distinctive natures of a great variety
of substances, plants, animals, tools, persons, etc., not only as
classes but as individuals.

What now is the mental process by which classification is effected?
Manifestly it is a recognition of the _likeness_ or _unlikeness_ of
things, either in respect of their sizes, colours, forms, weights,
textures, tastes, etc., or in respect of their modes of action. By some
special mark, sound, or motion, the savage identifies a certain
four-legged creature he sees, as one that is good for food, and to be
caught in a particular way; or as one that is dangerous; and acts
accordingly. He has classed together all the creatures that are _alike_
in this particular. And manifestly in choosing the wood out of which to
form his bow, the plant with which to poison his arrows, the bone from
which to make his fish-hooks, he identifies them through their chief
sensible properties as belonging to the general classes, wood, plant,
and bone, but distinguishes them as belonging to sub-classes by virtue
of certain properties in which they are _unlike_ the rest of the general
classes they belong to; and so forms genera and species.

And here it becomes manifest that not only is classification carried on
by grouping together in the mind things that are _like_; but that
classes and sub-classes are formed and arranged according to the
_degrees of unlikeness_. Things widely contrasted are alone
distinguished in the lower stages of mental evolution; as may be any day
observed in an infant. And gradually as the powers of discrimin