What are the optimal numbers or quantities of nations, people, languages, races, marriage partners, wealth, monies, criminals and other such phenomenon? This depends, of course, on the goals of the people answering this question. Two different perspectives will be employed in the present paper in order to wrestle with this question: the libertarian political philosophy, and what I shall categorize as prudential judgment, or economic welfare. For example, it would be unwieldy in the extreme, and unwise, to have a different monetary system for each of the some 7 billion inhabitants of earth; this would amount to no monetary system at all, or barter. Similarly, 7 billion different languages would mean communication would be impossible, surely not an ideal state of affairs from just about any perspective. But can we pin the numbers better down than this? That is the burden of the present paper.