I am afraid it would be dangerous to assume your familiarity with this system, and I must therefore begin with a brief description of its main characters. The essential feature of the classificatory system, that to which it owes its name, is the application of its terms, not to single individual persons, but to classes of relatives which may often be very large. Objections have been made to the use of the term “classificatory” on the ground that our own terms of relationship also apply to classes of persons; the term “brother,” for instance, to all the male children of the same father and mother, the term “uncle” to all the brothers of the father and mother as well as to the husband of an aunt, while the term “cousin” may denote a still larger class. It is, of course, true that many of our own terms of relationship apply to classes of persons, but in the systems to which the word “classificatory” is usually applied, the classificatory principle applies far more widely, and in some cases even, more logically and consistently. In the most complete form of the classificatory system there is not one single term of relationship the use of which tells us that reference is being made to one person and to one person only, whereas in our own system there are six such terms, viz., husband, wife, father, mother, father-in-law and mother-in-law. In those systems in which the classificatory principle is carried to its extreme degree every term is applied to a class of persons. The term “father,” for instance, is applied to all those whom the father would call brother, and to all the husbands of those whom the mother calls sister, both brother and sister being used in a far wider sense than among ourselves. In some forms of the classificatory system the term “father” is also used for all those whom the mother would call brother, and for all the husbands of those whom the father would call sister, and in other systems the application of the term may be still more extensive. Similarly, the term used for the wife may be applied to all those whom the wife would call sister and to the wives of all those whom the speaker calls brother, brother and sister again being used in a far wider sense than in our own language. The classificatory system has many other features which mark it off more or less sharply from our own mode of denoting relationship, but I do not think it would be profitable to attempt a full description at this stage of our enquiry. As I have said, the object of these lectures is to show how the various features of the classificatory system have arisen out of, and can therefore be explained historically by, social facts. If you are not already acquainted with these features, you will learn to know them the more easily if at the same time you learn how they have come into existence.