We are accustomed to say that the essential characteristic of the mental processes of man is the power of reasoning. While animals as well as man may perform actions suited to an end, based on memory of the results of previous actions, and suitable selection of actions fitting a certain purpose, we have no evidence whatever that would show that the abstract concepts accompanying the action can be isolated by animals, while all groups of man, from the most primitive to the most highly developed, possess this faculty. These few remarks on the common mental traits of man will suffice. When we turn to a consideration of the racial and social characteristics of the human mind, we find ourselves confronted by a peculiar difficulty. In all our thoughts we think in terms of our own social environment. But the activities of the human mind exhibit an infinite variety of form among the peoples of the world. In order to understand these clearly, the student must endeavor to divest himself entirely of opinions and emotions based upon the peculiar social environment into which he is born. He must adapt his own mind, so far as feasible, to that of the people whom he is studying. The more successful he is in freeing himself from the bias based on the group of ideas that constitute the civilization in which he lives, the more successful he will be in interpreting the beliefs and actions of man. He must follow lines of thought that are new to him. He must participate in new emotions, and understand how, under unwonted conditions, both lead to actions. Beliefs, customs, and the response of the individual to the events of daily life, give us ample opportunity to observe the manifestations of the mind of man under varying conditions. Apparently the thoughts and actions of civilized man, and those found in more primitive forms of society, prove, that, in various groups of mankind, the mind responds quite differently when exposed to the same conditions. Lack of logical connection in its conclusions, lack of control of will, are apparently two of its fundamental characteristics in primitive society. In the formation of opinions, belief takes the place of logical demonstration. The emotional value of opinions is great, and consequently they quickly lead to action. The will appears unbalanced, there being a readiness to yield to strong emotions and a stubborn resistance in trifling matters.