NATURE AND IMPORTANCE OF THE DOCTRINE OF FILIATION, OR DESCENT-THEORY.
General Importance and Essential Nature of the Theory of Descent as reformed by Darwin.--Its Special Importance to Biology (Zoology and Botany).--Its Special Importance to the History of the Natural Development of the Human Race.--The Theory of Descent as the Non-Miraculous History of Creation.--Idea of Creation.--Knowledge and Belief.--History of Creation and History of Development.--The Connection between the History of Individual and Palæontological Development.--The Theory of Purposelessness, or the Science of Rudimentary Organs.--Useless and Superfluous Arrangements in Organisms.--Contrast between the two entirely opposed Views of Nature: the Monistic (mechanical, causal) and the Dualistic (teleological, vital).--Proof of the former by the Theory of Descent.--Unity of Organic and Inorganic Nature, and the Identity of the Active Causes in both.--The Importance of the Theory of Descent to the Monistic Conception of all Nature.
The intellectual movement to which the impulse was given, thirteen years ago, by the English naturalist, Charles Darwin, in his celebrated work, "On the Origin of Species,"(1) has, within this short period, assumed dimensions which cannot but excite the most universal interest. It is true the scientific theory set forth in that work, which is commonly called briefly Darwinism, is only a small fragment of a far more comprehensive doctrine--a part of the universal Theory of Development, which embraces in its vast range the whole domain of human knowledge.
But the manner in which Darwin has firmly established the latter by the former is so convincing, and the direction which has been given by the unavoidable conclusions of that theory to all our views of the universe, must appear to every thinking man of such deep significance, that its general importance cannot be over estimated. There is no doubt that this immense extension of our intellectual horizon must be looked upon as by far the most important, and rich in results, among all the numerous and grand advances which natural science has made in our day.
When our century, with justice, is called the age of natural science, when we look with pride upon the immensely important progress made in all its branches, we are generally in the habit of thinking more of immediate practical results, and less of the extension of our general knowledge of nature. We call to mind the complete reform, so infinitely rich in consequences to human intercourse, which has been effected by the development of machinery, by railways, steamships, telegraphs, and other inventions of physics. Or we think of the enormous influence which chemistry has brought to bear upon medicine, agriculture, and upon all arts and trades.