Unless they coincide with clearly defined physical boundaries – as is the case, for instance, with Australia – the borders of a cultural area can rarely be established with ease and accuracy. To some extent the problem lies with the highly subjective and often purely emotional criteria by which a civilization is defined. Thus, for example, as these lines are written, many nations would place themselves within a larger community which they call the “free world,” while no attempt is made to define what freedom may mean to human beings with a cultural background different from their own. If there is a “free world” then, presumably, there must exist, in the minds of those who use the term, another world, “not free,” and the differentiation is contingent on an emotionally charged interpretation of the ill-defined term of “freedom.” It is a well-known rule of logic that classifications made on the basis of a single attribute are artificial and of limited use. So there must be a cluster of attributes by which a human group is defined, and these must be specific and essential, if they are to serve a useful purpose. Yet what is essential to one observer is not to another. Some would opt for language, others for race, religion, or shared destiny in the past or the present. It is also quite common to find that individuals tend to identify their own community by criteria which may be different from those used for the same purpose by outsiders.