WE have thus far succeeded in demonstrating that series of demographic data can be broken up into simpler series. We have shown that crude series reflecting the condition of humankind -- such as the birth-rate, death-rate, marriage, and divorce -- are the result of four distinct forces which it is possible to isolate. It is clear that it is possible to break up these large mysteries into smaller ones; and that it is possible to explain these simpler mysteries more clearly than is possible for the larger ones.1 In order to understand the relationship between these phenomena happening to men, we must remove certain influences before comparisons can be made. If we compare, for example, the fluctuations of the birth-rate with the fluc____________________
"The methods of such study are familiar; they are primarily descriptive and analytic. We call them scientific. They break up the big mystery into little ones; they sometimes succeed in reaching an immediate -- although never an ultimate -- rather satisfying explanation of some of these little parts of the big whole. By these methods we re-describe, which is a form of approximate explanation, these parts of the mystery and sometimes the whole mystery. If it is a mystery of life and so-called vital forces -- and no kind of mystery is more fascinating to us nor more feverishly discussed and studied than this kind -- we re-describe it, or bits of it, in terms of non-life, and of forces of physics and chemistry."