And, just as words and thoughts are essentially symbols, so there are also gesture-symbols and written symbols, whilst again another set of symbols is in use for counting.
All these pre-requisites of human intercourse may be conveniently taken together.
Coming now to the analysis of the forms of society, the beginner must first of all face the problem: "What makes a people one ?" Neither blood, nor territory, nor language, but only the fact of being more or less compactly organized in a political society, will be found to yield the unifying principle required.

Once the primary constitution of the body politic has been made out, a limit is set up, inside of which a number of fairly definite forms of grouping offer themselves for examination; whilst outside of it various social relationships of a vaguer kind have also to be considered.

Thus, amongst institutions of the internal kind, the family by itself presents a wide field of research; though in certain cases it is liable to be overshadowed by some other sort of organization, such as, notably, the clan.

Under the same rubric fall the many forms of more or less voluntary association, economic, religious, and so forth.

On the other hand, outside the circle of the body politic there are, at all known stages of society, mutual understandings that regulate war, trade, travel, the celebration of common rites, the interchange of ideas.