6

NATURAL SCIENCE AND RELIGION.

rather than of science, upon which the momentous question of theism or non-theism eventually turns. Some on the other hand are mere survivals, now troublesome only to those who are holding fast to theological positions which the advance of actual knowledge has rendered untenable, but which they do not well know how to abandon; yet which, in principle, have mostly been abandoned already.

To begin with trite examples. Among the questions which disquieted pious souls in my younger days, but which have ceased to disquiet any of us, are those respecting the age and gradual development of the earth and of the solar system, which came in with geology and modern astronomy. I remember the time when it was a mooted question whether geology and orthodox Christianity were compatible; and I suppose that when, in these quarters, the balance inclined to the affirmative, it was owing quite as much to Professor Silliman's transparent Christian character as to his scientific ability. One need not be an old man to know that Laplace was accounted an atheist because he developed the nebular hypothesis, and because of his remark that he had no need to postulate a Creator for the mathematical discussion of a

physical theorem; for a venerable and most religious astronomer, still living, who adopted this hypothesis in his "Exposition of certain Harmonies of the Solar System," published only five years ago, thought it needful to add an appendix, asking the question, "Is the nebular hypothesis, in any form, essentially atheistical in its character?" He answered it in the negative, but with the salvo, that "this hypothesis, having to do with a strictly azoic period, enforces no connection with the development theory' of the beginning or of the progress of life."

The great antiquity of the habitable world and of existing races was the next question. It gave some anxiety fifty years ago; but is now, I suppose, generally acquiesced in,-in the sense that existing species of plants and animals have been in existence for many thousands of years; and, as to their associate, man, all agree that the length of his occupation is not at all measured by the generations of the biblical chronology, and are awaiting the result of an open discussion as to whether the earliest known traces of his presence are in quaternary or in the latest tertiary deposits.

As connected with this class of questions, many of us remember the time when schemes

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for reconciling Genesis with Geology had an importance in the churches, and among thoughtful people, which few if any would now assign to them; when it was thought necessary- for only necessity could justify it to bring the details of the two into agreement by extraneous suppositions and forced constructions of language, such as would now offend our critical and sometimes our moral sense. The change of view which we have witnessed amounts to this. predecessors implicitly held that Holy Scripture must somehow truly teach such natural science as it had occasion to refer to, or at least could never contradict it; while the most that is now intelligently claimed is, that the teachings of the two, properly understood, are not incompatible. We may take it to be the accepted idea that the Mosaic books were not handed down to us for our instruction in scientific knowledge, and that it is our duty to ground our scientific beliefs upon observation and inference, unmixed with considerations of a different order. Then, when fundamental principles of the cosmogony in Genesis are found to coincide with established facts and probable inferences, the coincidence has its value; and wherever the particulars are incongruous, the discrepancy does not distress us,

I may add, does not concern us. I trust that the veneration rightly due to the Old Testament is not impaired by the ascertaining that the Mosaic is not an original but a compiled cosmogony. Its glory is, that while its materials were the earlier property of the race, they were in this record purged of polytheism and Natureworship, and impregnated with ideas which we suppose the world will never outgrow. For its fundamental note is, the declaration of one God, maker of heaven and earth, and of all things, visible and invisible, a declaration which, if physical science is unable to establish, it is equally unable to overthrow.

But, leaving aside for the present all questions of this sort, I proceed with the proper subject of this discourse; namely, the further changes in scientific belief, which have occurred within my own recollection, even since the time when I first aspired to authorship, now fortyfive years ago.

There will be no need to go much beyond the line of subjects which it has been my busi.ness to study, in order to bring before you, in a cursory review, not indeed all the disturbing topics of the time, but quite enough of them for our purpose. For the changes which we

have to consider are all more or less connected with the evolutionary theories which are now uppermost in the popular mind. In this presentation, it is best to set them forth in their simplest or most general form, divested of all theological or philosophical considerations, which have been or may be attached to them. I should rather say, to some of them. For the foundations, or at least the buttresses, of the now prevalent doctrine of the derivative origin of species mainly rest upon researches independently made, without speculative bias, being the general contributions to biological science in this century; the results of which have been accepted as far as made out without apprehension or other than scientific controversy.

Upon no one of these particular points has there been a completer change of view than upon the distinctness of the animal and vege-` table kingdoms. The former conviction that these two kingdoms were wholly different in structure, in function, and in kind of life, was not seriously disturbed by the difficulties which the naturalist encountered when he undertook to define them. It was always understood that plants and animals, though completely contrasted in their higher representatives, approached each

other very closely in their lower and simpler forms. But they were believed not to blend. It was implicitly supposed that every living thing was distinctively plant or animal; that there were real and profound differences between the two, if only they could be seized ; and that increased powers of investigationmicroscopical and chemical- might be expected to discover them. This expectation has not been fulfilled. It is true that the ambiguities of a hundred years ago are settled' now. The zoophytes are all remanded to their proper places, though the animal kingdom at first claimed more than belonged to it. But other, more recondite and insurmountable, difficulties arose in their place. The best, I am disposed to say the settled, opinion now is, that there are multitudinous forms which are not sufficiently differentiated to be distinctively either plant or animal, while, as respects ordinary plants and animals, the difficulty of laying down a definition has become far greater than ever before. In short, the animal and vegetable lines, diverging widely above, join below in a loop. Naturalists may help classification, but do not alter these facts, when they sever this loop arbitrarily at what they deem the