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The modern doctrine of evolution is generally dated from the publication, in 1859, of Charles Darwin's "Origin of Species.” But no great idea comes out of the blue sky. Darwin himself prefixed to the second edition of his "Origin" an historical sketch of the theory of evolution up to his time. Many authors have since done this more thoroughly from the appearance of some sort of evolutionary view in Aristotle down to the modern period. But Darwin's decision not to go back of the nineteenth century with his sketch was sound. For though one may mention Aristotle, Lucretius, Augustine, and Aquinas as men who had a passing glimpse of the larger view, they had not got hold of evolution in its modern sense. Each guess was a leap in the dark, with no exact or detailed knowledge back of it just an inkling that the visible universe with all that it contains was too vast and complicated to be satisfactorily accounted for by any explanation hitherto offered.

"See especially, Henry Fairfield Osborn's From the Greeks to Darwin.


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The view of Dr. John Lightfoot, Vice Chancellor of the University of Cambridge, "that heaven and earth, center and circumference, were created altogether, in the same instant, and clouds full of water, and that this work took place and man was created by the Trinity on October 23, 4004 B.C. at nine o'clock in the morning" 2 would have repelled them by its pseudo-simplicity. But of evolution in the modern sense, these older thinkers did not even surmise.

Nevertheless, it is evident that the world had been getting ready, for some time, for the idea of evolution. The old astronomy, with the earth as the center of the universe, had been outgrown. As truly as Galileo, many other men of his time knew that the earth did move. Newton had deduced his law of gravity, which proclaimed that at least one law held good in the entire realm of space. Kant had published his nebular hypothesis, and LaPlace had put his mathematical knowledge into its elaboration. Beacon, Pascal, and Descartes had accustomed men to the idea that human history was a gradual upward process. Leibnitz's “monistic idea of the substantial similarity of all things” broke down many of what were thought to be impassable barriers between one sort of thing and another. Buffon (1707-1788) consented to be specific, in quite the modern fashion, and proved to his own satisfaction that the domesticated pig, at least when fresh from the Creator's hand, did not look and behave as he now does. But how far in his own mind he generalized this idea to include the rest of the animal creation, he was too cautious to let anyone know.

* Andrew D. White, A History of the Warfare of Science with Theology in Christendom, vol. I, pp. 4, 9.

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In 1801 Lamarck had been so much impressed with the difficulty of distinguishing the very fine shades of difference between many species and varieties, that he concluded that "all species, not excepting man, were descended from other species.” The changes in bodily structure, he thought, were the result of changes in the environment, which forced the animal to make changes in his habits, that were registered in his body and handed down by inheritance. One Englishman of note was converted to this theory of LamarckCharles Darwin's grandfather, Dr. Erasmus Darwin. Lamarck's work was not widely read in England. Neither was Dr. Darwin's exposition of it, for he turned it into a long poem, and it made slow headway among English scientists. Another contributor was Robert Chambers in his book, "Vestiges of the Natural History of Creation,” 1844, which ran through ten editions. Darwin speaks of its "brilliant and powerful style, though displaying in the earlier editions) little accurate knowledge and a great want of scientific caution." In Darwin's opinion, however, this book did "excellent service in calling attention to the subject and in removing prejudices." A glance at Mr. Chambers' outline shows us the arguments which in an improved form have since become so familiar, the similarity of structure among vertebrate animals, the homologies, the variability of existing species, the argument from fossil remains, and from embryology. In 1855, Herbert Spencer published his statement of physical evolution which now forms part of the first volume of his "Principles of Biology.” It is still profitable reading, which is more than can be said of most books when they approach the age of seventy, and Karl Pearson in a recent bibliography still


recommends it, though he adds that it is to be read “with caution."

Several other factors helped, quite as much as these direct attempts, to establish the doctrine of evolution. The geologists had immensely extended the age of the earth. Agassiz, though he never became an evolutionist, confessed that all well-informed naturalists believed that “this globe had been in existence for innumerable ages, and that the time which had elapsed since it first became inhabited, cannot be counted in years." Astronomers had come to believe that the earth had been formed out of a ring of star-dust that had broken away from the sun, and they were very sure that this had not happened recently.

Men were also finding great difficulty with the growing contradictions between many things which they knew, and more which they were continually finding out. Tradition held that God had created each species by an act of special creation. But the number of species kept multiplying. A hundred years before Darwin, Linnæus had enumerated four thousand distinct species of animals. This meant not merely that God had created these by four thousand separate special acts of creation, but that Adam had given them four thousand different names and that Noah had gathered all four thousand into the ark. But other naturalists kept adding to the number of species all the time. Did the one hundred and sixty species of shells found on one little island mean that one hundred and sixty different acts of creation had taken place on that one little spot? Other items were quite as puzzling. If the kangaroo was in the cargo of the ark, how did he get to Australia, which is not at all near Ararat? Still more, why is he now confined to Australia, and the portions of the earth contiguous to Ararat free altogether of him? If the answer be that perhaps there had once been land-connection between Asia Minor and Australia, on which the kangaroo had crossed over, then why had no lions, or tigers, or rabbits, followed him across, and none of his relatives stayed behind? Thus, with new knowledge about species that were and were not to be found in distant parts of the earth, the doctrine that they had all been created, at one time, and just as they are now, became more and more difficult to hold.

One other idea re-inforced these influences at work among scientific men. The great geologist Lyell had laid down the principle that the present must explain the past. It must be assumed, in other words, that those same forces which can be seen at work all around us today, were at work in the past; therefore, if these forces, given time enough, are found sufficient to account for the changes by which the past has become the present, one had no right to resort to other agencies. A simple principle, surely—and obviously sensible.

This is a main reason why the publication of Darwin's "Origin of Species” gave the doctrine of evolution a totally different standing among scientific men. By the use of Lyell's principle, he showed how evolution had happened, backing up its demonstration with such a wealth of painstaking observation and accurate knowledge as had never been gathered to gether in one place before. His chief steps are perfectly simple. Every animal is in general like its ancestors; in other words, there is a principle of heredity. But no animal is ever exactly like its ancestors; there is the fact of variation. Breeders, he pointed

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