Theologians have dreaded the establishment of the theories of Darwin and Spencer, as if they thought that those theories could explain everything upon the purest mechanical and material principles, and exclude all notions of design.  They do not see that those theories have opened up more questions than they have closed.  The doctrine of evolution gives a complete explanation of no single living form.  While showing the general principles which prevail in the variation of living creatures, it only points out the infinite complexity of the causes and circumstances which have led to the present state of things.  Any one of Mr. Darwin's books, admirable though they all are, consists but in the setting forth of a multitude of indeterminate problems.  He proves in the most beautiful manner that each flower of an orchid is adapted to some insect which frequents and fertilises it, and these adaptations are but a few cases of those immensely numerous ones which have occurred throughout the life of plants and animals.  But why orchids should have been formed so differently from other plants, why anything, indeed, should be as it is, rather than in some of the other infinitely numerous possible modes of existence, he can never show.  The origin of everything that exists is wrapped up in the past history of the universe.  At some one or more points in past time there must have been arbitrary determinations which led to the production of things as they are. -- The principles of Science.  By Professor Jevons.