That language is an ethnographic document of fundamental importance is a plain truism. It also hardly needs stressing that the knowledge of all aspects of tribal life, without exception, is essential to a sound knowledge of any one aspect. To omit, for instance, the study of religion, or economics, or social organization when dealing with a native society, results not only in our ignorance of the subject omitted, but also lowers the value of all that has been recorded. All aspects of tribal life play into each other; to sunder a few of them from the rest results in a mutilation of the whole, and language is not an exception in this respect. The study of the linguistic aspect is indispensable, especially if we want to grasp the social psychology of a tribe, i.e. their manner of thinking, in so far as it is conditioned by the-peculiarities of their culture. All this is clear and well known.