SCIENCE IN THE LAST HALF CENTURY. 83 



edge to unify itself, which has led to the doctrine of the conservatiou of 

 energy. And this tendency, again, is mainly a product of the increas- 

 ing strength conferred by physical investigation on the belief in the 

 universal validity of that orderly relation of facts, which we express by 

 the so called "Laws of Nature." 



The growth of a plant from its seed, of an animal from its egg, the 

 apparent origin of innumerable living things from mud, or from the 

 putrefying remains of former organisms, had furnished the earlier sci- 

 entific thinkers with abundant analogies suggestive of the conception of 

 a corresponding method of cosmic evolution from a formless "chaos" 

 to an ordered world which might either continue forever or undergo 

 dissolution into its elements before starting on a new course of evolu- 

 tion. It is therefore no wonder that, from the days of the Ionian school 

 onwards, the view that the universe was the result of such a process 

 should have maintained itself as a leading dogma of philosophy. The 

 emanistic theories which played so great a part in Neoplatonic philos- 

 ophy and Gnostic theology are forms of evolution. In the seventeenth 

 century, Descartes propounded a scheme of evolution, as an hypothesis 

 of what might have been the mode of origin of the world, while pro- 

 fessing to accept the ecclesiastical scheme of creation, as an account of 

 that which actually was its manner of com.ing into existence. In the 

 eighteenth century Kant put forth a remarkable speculation as to the 

 origin of the solar system, closely similar to that subsequently adopted 

 by Laplace and destined to become famous under the title of the "neb- 

 ular hypothesis." 



The careful observations and the acute reasonings of the Italian 

 geologists of the seventeenth and eighteenth centuries, the specula- 

 tions of Leibnitz in the " Protogtea" and of Bufitbn in his " Th6orie de 

 la Terre," the sober and profound reasonings of Hutton, in the latter 

 part of the eighteenth century,— all these tended to show that the 

 fabric of the earth itself implied the continuance of processes of natural 

 causation for a period of time as great, in relation to human history, as 

 the distances of the heavenly bodies from us are, in relation to terres- 

 trial standards of measurement. The abyss of time began to loom as 

 large as the abyss of space. And this revelation to sight and touch, 

 of a link here and a link there of a practically infinite chain of natural 

 causes and effects, prepared the way, as perhaps nothing else has done, 

 for the modern form of the ancient theory of evolution. 



In the beginning of the eighteenth century, De Maillet made the first 

 serious attempt to apply the doctrine to the living world. In the latter 

 part of it, Erasmus Darwin, Goethe, Treviranus, and Lamarck, took up 

 the work more vigorously and with better qualifications. The question 

 of special creation, or evolution, lay at the bottom of the fierce dis- 

 putes which broke out in the French Academy between Cuvier and St.- 

 Hilaire; and, for a timn, the supporters of biological evolution were 

 .silenced, if not answered, by the alliciuce of the greatest naturalist of 



