Abstract
One of the reasons which has induced philosophers to enquire about animal psychology is the hope of arriving at a more precise understanding of human mental faculties. For example, in relatively recent times, this motive was evident among various authors of the seventeenth century, who were more or less directly influenced on the issue by Descartes. Over and above the varying lines which they pursued, what they most often have in common, is an essentially anthropocentric approach to the study of animals. The general categories which they used were mainly defined by specific reference to “human nature,”. The identity of this nature was to be highlighted by the complex of differences from, and similarities to, that of the animals.