It was Adolphe Quetelet, Astronomer-Royal of Belgium, who in the seventies of the last century attempted to prove that "_the average man is to a nation what the centre of gravity is to a body_." A similar, if not quite the same, conclusion has since been reached by Sir Francis Galton and Professor Karl Pearson in their researches into men's physical and intellectual qualities in the light of Darwin's theory of Natural Selection or Survival of the Fittest. This theory which, in its more extended form, is called the Law of Evolution, has profoundly influenced, if not entirely revolutionized, the Science and Philosophy of our own times. It has _not_ however succeeded, as was at first feared, in destroying men's belief in God, the Creator and Ruler of the Universe. For it has done no more than disclose but a few of the numerous ways in which He creates and rules. I have been a student of Evolution Literature ever since I left College. Speaking for myself I can say that my study of it has not in the least shaken my belief in God, but has rather strengthened it. I entirely agree with a popular writer[78] on "the Scientific Ideas of To-day," who says: "True Science does not seek to deprive man of his Soul or to drive the Creator from his Universe, but it honestly endeavours to study His marvellous works ... to see the manner in which He has caused Nature to work out His design." The Law of Evolution or the Development Hypothesis, as it has been called, is in fact a clever guess at truth--very valuable as a formula which enables us not only to remember the result of numerous observations and experiments, but also to predict certain events to be verified by subsequent observations and experiments. It is impossible to convey a clear idea of it in a few sentences. A great man like Herbert Spencer spent 50 years of his life in explaining and illustrating it in no less than ten stout volumes of his "Synthetic Philosophy." The central idea may however be expressed in the following propositions, using the word "_thing_" in its widest sense as any object of perception, or knowable objects[79]. 1. Nothing exists absolutely by itself; everything exists in relation with something else which is its "environment." 2. A thing and its environment cannot exist side by side for any considerable time without each affecting or influencing the other in some respects at least: a thing A and its environment B, which cannot but exist together, must needs act and re-act on each other. [Illustration] 3. The action and re-action of the thing A and its environment B on each other, brings about mutual adjustment, the fitting of each into the other. 4. According as this mutual adjustment or fitting is relatively _complete_ or _incomplete_, there is Evolution or Dissolution, survival or extinction, of the thing (A) itself.[80] 5. The process of Evolution or Survival is characterized by:--