er, Al-Gazzali
(A.D. 1010).

In a stone the material particles are in a state of stable equilibrium;
it may, therefore, endure forever. An animal is in reality only a form
through which a stream of matter is incessantly flowing. It receives its
supplies, and dismisses its wastes. In this it resembles a cataract,
a river, a flame. The particles that compose it at one instant have
departed from it the next. It depends for its continuance on exterior
supplies. It has a definite duration in time, and an inevitable moment
comes in which it must die.

In the great problem of psychology we cannot expect to reach a
scientific result, if we persist in restricting ourselves to the
contemplation of one fact. We must avail ourselves of all accessible
facts. Human psychology can never be completely resolved except through
comparative psychology. With Descartes, we must inquire whether the
souls of animals be relations of the human soul, less perfect members in
the same series of development. We must take account of what we discover
in the intelligent principle of the ant, as well as what we discern in
the intelligent principle of man. Where would human physiology be, if
it were not illuminated by the bright irradiations of comparative
physiology?

Brodie, after an exhaustive consideration of the facts, affirms that
the mind of animals is essentially the same as that of man. Every one
familiar with the dog will admit that that creature knows right from
wrong, and is conscious when he has committed a fault. Many domestic
animals have reasoning powers, and employ proper means for the
attainment of ends. How numerous are the anecdotes related of the
intentional actions of the elephant and the ape! Nor is this apparent
intelligence due to imitation, to their association with man, for
wild animals that have no such relation exhibit similar properties. In
different species, the capacity and character greatly vary. Thus the dog
is not only more intelligent, but has social and moral qualities that
the cat does not possess; the former loves his master, the latter her
home.

Du Bois-Reymond makes this striking remark: "With awe and wonder must
the student of Nature regard that microscopic molecule of nervous
substance which is the seat of the laborious, constructive, orderly,
loyal, dauntless soul of the ant. It has developed itself to its present
state through a countless series of generations." What an impressive
inference we may draw