Here, then, we have a process of degradation by which the different races of animals were formed, by a kind of selection which, commencing in the human species from the neglect of the encephalic soul to maintain its high duties and aims, goes on in successive debasements which result in the formation of lower and still lower animals until we reach the shell-fish fixed upon the earth at the bottom of the water. The bi-sexual principle of construction having been introduced in the human species, was continued through all the other species formed by the still descending process of deterioration, so that to each successive species there remained the power of reproducing its own type, along with the tendency to evolve a lower type by further loss of reason or rationality. It is not material to the purpose of the parallel, which I am about to draw between the Platonic and the Darwinian system, to consider the precise nature of the Platonic idea of an intelligent power, by which these successive degradations were in one sense purposely ordained. Enough is apparent on the Platonic system to show that, while these degradations were according to an eternal plan, because they resulted from the conflict between reason and unreason, order and disorder, between purity and impurity, yet the different species of animals, after man, were not special creations by an infinite power interfering in each case by a separate exercise of creative will. They were a growth of an inferior organization out of a superior through the inevitable operation of tendencies which changed the forms of the animals. As fast as these tendencies operated--and they were continually operating--the ministers of the Demiurgus, the gods, stood ready to adapt the structure to the new conditions in which the tendencies resulted, so that the new animal might be fitted to and fixed in those conditions. Still, the gods are not represented as making separate creations of new species as an act of their will, without the pre-existing operation in the preceding type of tastes and occupations which modify the structure into one of a more degraded character. It may thus be said with entire truth that the Platonic idea of the origin of the different races of animals presents a parallel to the Darwinian theory, in which it will be found that the one is the reverse of the other, both of them proceeding upon and involving analogous principles of evolution, operating in the one system from below upward, and in the other from a higher point downward. If, in the Platonic system, the idea of an original immortal soul placed in a heavenly abode, but afterward brought down and fixed in a mortal body, is the starting-point--if a conflict of a spiritual and angelic existence with corporeal and earthly tendencies is at first the predominant fact--the parallel between the Platonic process of degradation and the Darwinian process of elevation remains the same;