After studying each of the factors of society as far as possible apart from the others, it is next in order to study them as they work together to make a self-sustaining whole: how population becomes organized in groups of various sizes and for various purposes, according to the kind of communication which unites them, the groups and the communication again depending on the qualities of the individuals and the kinds of activity in which the location and the density of population compel them to engage. This Part II includes the most substantial portion of sociology: it is the portion which has been most thoroughly worked out and so has the most of scientific character. If we wish to see society reduced to its lowest or most general terms and still remain society (the test of that being whether or not the terms are treated in any other science than sociology), then here is the place to rind it. Part I was obviously only introductory to this.