THE HISTORY OF ANIMAL PSYCHOLOGY According to the conception of primitive peoples, man is in some way related to the animal world which surrounds him. Every person has his symbolic animal, his totem, into which he believes he is changed at death. This animal represents the embodiment of the soul, either of individuals or of the whole race. For this reason it is sacred and may not be hunted. Gods in ancient Egypt and in India had human bodies of gigantic proportions with the heads of animals. Apes and other animals kept in the temples were considered holy. The belief in a migration of souls through different animals has always been widespread. All of these points of view are based upon the assumption that the animal soul is closely related to the human soul, that there exists no essential difference between the two. The ancient Greek philosophers, too, who engaged in detailed discussions of the animal soul were dominated by the belief in an essential relationship to men. It is true that the belief that the animal soul is on a lower level than the human soul makes itself gradually more and more felt_ The Pythagoreans and Empedocles, on the contrary, believed in a transmigration of souls with intermediate stages in animals. The natural philosophers, the Epicureans, and later Lucretius Carus and Plutarch, ascribe more or less human attributes to ani mals. Particularly in Plutarch do we find many examples, in the nature of anecdotes, purporting to demonstrate the intellect, memory, deliberation and reason of animals. Quite a number of really good observations are included in these tales. This purely anthropomorphic mode of thought was maintained by individual thinkers for a long period. The neo-platonist Porphyrius sub scribed to this view and even as late as the r6th century Mon taigne used it to humble the pride of man. In the 18th century, Condillac and Leroy were influenced by the same idea.
Parallel to this humanizing conception another point of view made itself felt quite early in Greek philosophy, maintaining that there is a great and unbridgeable gap between human and animal souls. The great exponents of idealistic philosophy, Socrates, Plato and Aristotle, insisted on the distinction between man and beast, as did the Stoics. They denied the faculty of thought to animals. According to Aristotle, man possesses a reasoning soul (anima intellectualis), and, in addition, a purely sensory soul (anima sensitive), whereas animals possess the latter alone. An
animal is gifted only with the faculties of sensation and move ment, while man has, in addition, the power of thought and understanding. He alone has an immortal soul. This great cleft in the modes of conception of the animal soul continued until long after the middle ages. The middle ages were dominated by the teaching of the Church which was strongly influenced by Aristotle. In the same way as the Greek philosopher, the Scholas tics differentiated between a sensory and a reasoning soul, the latter being present in man alone. Instinct was considered to be a contrivance of nature permitting the animal to perform pur poseful actions without understanding the reason for its be haviour. Further, sense-perception and sense-memory were as cribed to animals, while man had, in addition to this, intellectual perception and true memory. Descartes (Cartesius, 1596-165o), too, thought that animals had no share in the intellectual sub stance. They ranked as mere machines.
As early as the 16th and 17th centuries a number of thinkers, such as Montaigne, Rotarius, Thomasius, Jenkin, opposed them selves to this conception of rigid instincts. They conceded mem ory and comprehension to animals and thus pointed the way to a new animal psychology. The view taken during the English and French period of enlightenment of the 17th and i8th centuries was also in sharp opposition to the mediaeval idea of instinct, although it had been arrived at in quite another manner. The sense-impressions and perceptions were here considered to be the basis of thought. The distinction between a thinking and a per ceptive soul no longer held. According to Hume animals are able to store up sensory impressions and make experiences. But in addition, they possess numerous inborn instincts. The differences between animal and human modes of thought are gradual only. In the century tne tendency made itself felt, under the in fluence of the free-thinkers, to avoid the word instinct altogether, for there was once more a movement towards an anthropo morphism which soon became unbounded and conceded thought and feeling to animals in the same way as to man. This was the period in which Alfred Brehm, Karl Voigt and others attempted to bring animals and man together.