We have adduced some of the illustrations which physical and physiological science affords of the Law of Universal Development: let us close this part of our subject with the illustrations afforded by the rise and progress of Science as a whole. The first germs of science were very simple, existing in connection with Art, and subserving the purposes of priestcraft. For a long time the range of scientific inquiry was so limited that the same individual was able to grasp it entire. But one branch after another has sprung up, diverging more and more into the realms of the unknown, until no one mind can hope to obtain even a general knowledge of them all.
But this has not been the only tendency of scientific growth. Divergence and differentiation had not proceeded far till the combining and organizing movement began. The more individuality and complexity have threatened to outreach the mental powers and become unmanageable, the more have order and organization shown their ability to subordinate and unitize the seeming diversity of elements. While the sciences continued to increase in number and complexity, they began to overlap and interlace, the principles of one running into the domain of another, and even coördinating and binding together its seemingly incongruous parts.
A simple scientific generalization is based on certain facts which, taken in their collective capacity, mean the truth which is expressed in the formula. A higher generalization embraces those which are simpler, and unites by its expression the truths which they contain into the formula of one great truth. This process goes on, rising constantly higher and higher, the generalizations of the ascending series becoming more comprehensive, and the convergence of all the diversified elements into great general laws more striking and complete. Thus advances the unitizing movement of science; and it is now progressing with a steadiness and certainty unknown in former periods of research. Great minds are at this moment occupied in the discovery and verification of these great unitizing laws. Thus we perceive, that while science has developed a bewildering mass of individual facts and minor principles, it has also developed the germs of a unity which is destined to unfold with a richness and magnificence of result heretofore unknown in the annals of human inquiry.