Part 7

It is not here suggested that all scientific men would employ such language as that now quoted, or even readily acquiesce in its use. I have been careful to indicate, that a passionately excited antagonism to any recognition of the supernatural is avowed by some scientific men. Accordingly, it must be granted that the conclusion here stated is not so manifest a deduction as to preclude denial. The testimony of the senses commonly terminates dispute, but such testimony is not available as to the reality of the supernatural. The only testimony that can be given here must be of a different kind; and if there be some who refuse to credit anything save what comes within range of the senses, or is deducible directly and simply from what the senses make known, there is no help for them. Neither science, nor philosophy, nor religion can deliver them from the narrow round of materialism. But neither science, nor philosophy, nor religion, can restrict itself to the testimony of the senses. A deeper, and wider range of inquiry is demanded of the man who would walk at large in the vast field spread out in nature. All human life is subjected to the test of accepting evidence other than that the senses supply. If some refuse to submit to this deeper and wider test, narrowing their convictions accordingly, others are not to be restricted in this way, nor are they to be influenced by such determination even on the part of highly distinguished scientific men. For, it can not be overlooked that this is not a question of science, nor does it imply any thing but an ordinary exercise of intelligence. The one test for the public mind is this,--Is it or is it not true that not an atom of matter can be originated or destroyed? Is the doctrine of the conservation of energy to be taken as scientifically demonstrated? These things science must decide, and beyond these, all is clear for ordinary intelligence. Of the testimony of science on these two questions there is no doubt whatever. Religion, therefore, has no conflict with science here; it simply accepts the teaching of science, finding in it ample support for its fundamental position. What creation really means, or how we can fittingly represent it to our minds, does not in the least affect the question here under discussion, for these are not points on which science can offer any testimony. Nor have the defenders of religion any complaint to urge against the claims which science makes to explain all that belongs to nature. But when those who make the largest claims for science, acknowledge that science is baffled here, their testimony gains in value by reason of the strength of their antipathy to the acknowledgment of the miraculous. When from an accredited scientific witness we have these words:--"The investigation of nature does not shrink from enrolling life and the processes of life in the world of the comprehensible," followed up by this explicit statement, "We are foiled only at the conception of matter and force";[AN] the claims of science are raised to the highest pitch; and yet its insuperable limits are clearly defined. The defender of the harmony of scientific with religious thought has nothing more to desire. The very place where science comes to a halt, acknowledging that its utmost boundary has been reached, is the place where it is demonstrated that scientific thought and religious are not involved in real conflict.

FOOTNOTES:

[AB] These allowances may well be made for Professor Clifford, one of the most extravagant assailants of religious faith.

[AC] Professor Tait in answer to Mr. Froude has advanced the evidence. _International Review_, Nov. 1878, vol. v. No. 6. The collected papers have been republished, _Atlas Series_, No. 11.

[AD] _Recent Advances in Physical Science_, by P. G. Tait, Professor of Natural Philosophy, University of Edinburgh, p. 17.

[AE] _Ib_. p. 2.

[AF] _Recent Advances in Physical Science_, p. 14.

[AG] See Appendix III.

[AH] _The Conservation of Energy_, by Balfour Stewart, p. 26.

[AI] _The Conservation of Energy_, p. 36.

[AJ] _Recent Advances of Physical Science_, p. 17.

[AK] Tait's _Recent Advances_, p. 15.

[AL] _Recent Advances_, p. 20.

[AM] _Recent Advances_, p. 22.

[AN] _The Doctrine of Descent_, by Oscar Schmidt, p. 20.

LECTURE IV.

ORGANIZED EXISTENCE: LIFE AND ITS DEVELOPMENT.--(DARWIN'S "THEORY OF EVOLUTION.")

In prosecuting our inquiry as to the most recent advances in science, we pass now from inorganic to organic existence; from the testimony of physicists, to that of zoölogists. This transition in itself starts a scientific problem, beyond which we are carried onward to a distinct and very complicated area of existence, higher in order, and pressing upon attention an incalculable variety of details, exceedingly difficult to harmonize. In the earlier stage of physical research, all observation and experiment lead forward to general results, which gain ready acceptance because they may be said to be involved in scientific procedure itself. In this more advanced stage it is otherwise. In the former, unorganized matter is the same everywhere; and the laws of energy can be studied with equal facility in Europe or in America, in northern latitudes or in southern. But when we begin to direct attention upon life in its manifold forms, as these are scattered all over the world, multitudes of distinct observations have to be prosecuted, and their results slowly accumulated, before even the most competent workers can occupy a position from which it is possible to make a beginning with our forecast of general conclusions. Even in the most favorable circumstances, a great deal must be left to problematic inference, and even to imagination. Gatherings of facts may be recorded in a manner which places them beyond reach of doubt, while theories founded upon them hang long in suspense, waiting confirmation on condition of being able to endure protracted criticism, and manifold applications. This accounts for the difficulty experienced in finding ready to hand general conclusions which have secured universal acceptance, when we begin to move somewhat freely over the wide regions presenting the manifold problems of organized existence. And as it is solely with general conclusions, that religious thought is concerned, some share of perplexity must attach to the attempt to discuss the question of harmony. We must here therefore be considerably involved in questions affecting theories which have gained wide favor in scientific circles, as well as with clearly recorded and certain results. Some general questions, such as that affecting the classification of animals, must be regarded as peculiarly scientific. Whether the classification of Linnæus, or of Cuvier, or some other more recently suggested, is to be preferred, is a matter which does not here concern us. But a theory of the origin of species must be considered, because it is not purely scientific, but brings science into direct relation with common thought as to the order of the universe, and may therefore stand related to religious thought.

Immediately on directing attention to organized existence,--to LIFE in any form,--we encounter a new problem, namely the relation of the organized to the unorganized. How is the appearance of this higher order of existence to be accounted for? Can we find in the nature of matter, and in the mechanical and chemical laws influencing its position and combination, any explanation of the appearance of life in the world? Or must we regard life as a new and higher fact, unexplained by reference to the lower form of existence, and incapable of explanation in this way? Whether there is a clear line of demarcation between vegetable and animal life is a comparatively subordinate question. It is the wider and more perplexing question which most fundamentally affects our general conceptions as to the history and government of the world? And when this question is pressed singly,--how can we account for the appearance of life in the world?--science has no answer to present. Life still remains a mystery in scientific times, as it had been in past ages. Much has been written as to the origin of species; nothing to any purpose has yet been said as to the origin of life itself. The secrets of the universe in this respect have eluded discovery, and a constrained silence is the consequence.

But if science itself has nothing to say as to this fundamental problem, scientific men have much to say as to the probability of a true solution of the mystery being forthcoming. There is in many quarters an expectation that we may yet understand the physical principles, that is, the mechanical and chemical combinations, which go to explain life as a working organism.[AO] The suggestions of Rumford and Joule may yet bear results in this direction, for it is matter of general agreement that living organism may be regarded as an engine doing a given amount of work, on condition of being supplied with a given amount of fuel in the form of nourishment. When therefore Rumford suggests that the animal is a more economical engine than any of the mechanical contrivances which man constructs, and when Joule advances considerably beyond this to suggest that the animal more resembles an electro-magnetic engine, than a heat engine, it seems quite within the range of possibility that in some such direction discovery may yet be made of the physical principles involved in life.

This, however, leaves untouched the deeper question as to the _origin of life_. We are entirely ignorant of any beginning of life which is not traced directly to a preceding living organism. Either, as in the case of plants, there is increase of life by fission, or separation from an earlier growth, or by means of seed grown upon the parent plant; or, as in the case of animals, by germ or ovum. But the question of the origin of life is remote from us historically, and perplexing to us experimentally. If we seek guidance historically, we turn to geology, and learn that the structure of the earth has involved successive formations. The materials of the earth's crust are not thrown together confusedly, but "exhibit a certain order of arrangement";[AP] the mineral masses are partly aqueous, partly igneous, in formation; according as they are one or other, they contain organic remains, or are marked by their absence. All that can be inferred from the data thus afforded is that at a certain period in the world's history, when temperature and other conditions affecting the possibility of organic existence were favorable, life appeared. As to the cause of its appearance, geology can give no testimony. If next, we refer to palæontology, we learn of the existence of colossal animals which have long since become extinct; but such researches only widen our acquaintance with different orders of animals, contributing nothing towards the solution of the problem concerning the origin of life. The experimental science of the present day, with all the advantages arising from microscopical observation, is altogether unable to offer any explanation. Experiments for the purpose of testing the probability of "spontaneous generation" have been already described, and their failure leaves experimental science without any direct testimony; while their history yields powerful indirect evidence in support of the position that origin of life apart from germ is unknown.

It is, however, desirable here, in order to give completeness to our view of the present situation, to remark that among scientific men there are some who have no expectation of a scientific explanation of the origin of life; while others are exceedingly hopeful that such explanation may be reached, in the latter class appearing naturally all those who openly proclaim against what they name an "incomprehensible act of creation," and voluntarily place themselves in antagonism to religious thought. It is, therefore, of some consequence to indicate the grounds on which such opposite views rest. On the one side, Professor Tait, while suggesting the possibility of yet discovering the physical principles which determine life, nevertheless adds, "Let no one imagine that, should we ever penetrate this mystery, we shall thereby be enabled to produce, except from life, even the lowest form of life."[AQ] On the other hand Professor Schmidt of Strasburg maintains the opposite view, affirming that "the investigation of nature does not shrink from enrolling _life_, and the processes of life in the world of the comprehensible."[AR] This latter assertion is not to be accounted for on the ground that Schmidt is the ardent admirer and defender of the theory of origin of species by natural selection, for it is clear, as he maintains in replying to Max Müller, that "the origin of life has in fact nothing to do with actual Darwinism, or natural selection, unless the principle of selection be extended to the inorganic world of matter."[AS] Mr. Darwin himself does not suggest any such extension, and his theory of species is not chargeable with it. It should, indeed, be clearly recognized on all hands that the naturalist confines himself to a narrower range of inquiry, taking existing phases of life as the subject of his study. Accordingly, whoever claims that the origin of life comes within the compass of science, does so on the ground that there is no demarcation between the organic and the inorganic,--that the former may arise directly from the latter,--and so he commits himself to a doctrine of descent world-wide in its application, involving development in the world of all its varied phases of existence from a mass of unorganized matter.

This explains the difference of opinion among scientific men as to the possibility of accounting for the origin of life. A certain number deny the possibility, as they do the possibility of explaining scientifically the origin of matter on the explicit ground indicated by Laplace,--"Present events are connected with the events of the past by a link resting on the obvious principle, that a thing can not begin to exist without a cause which produces it."[AT] They do not find in inorganic matter sufficient cause to account for life, and their expectations are restricted accordingly. Those who cherish a contrary expectation, do not vindicate it by contradiction of the obvious principle enunciated by Laplace, or even by maintaining that inorganic matter is adequate to produce living organism. They cling to the more general and doubtful position that no limits are to be assigned to science, or as it is often stated, all nature belongs to the comprehensible. The failure of past experiments is no proof that inevitable failure awaits other experiments which may yet be made. To abandon expectation seems to them to be unfaithful to science. In this fashion, Professor Schmidt declares that "to any one who holds open the possibility that, even now, animate may be evolved from inanimate, without the mediation of progenitors, _the first origin of life in this natural method is at once self-evident_."[AU] To this view the other side may legitimately reply, that if the origin of life be as easily accounted for, as provision is here made for the "self-evident," science will soon be at a discount. To those regarding the matter from without, and waiting for testimony as to what is scientifically established, it is clear that there is no explanation of the origin of life; and I think it will be most commonly held that the weight of reason as to expectations for the future lies with those who abandon the anticipation of any scientific explanation. There is, however, in actual conclusions on scientific evidence nothing involving conflict with religious conviction; and allowance will be made for continued and extended experiments, provided only that the "holding open the possibility," does not make the probability "self-evident."

Passing thus from the unsolved problem of the origin of life,--with the attendant acknowledgment that there is no scientific theory of the world's descent from primordial atoms, we advance to the testimony of science concerning different orders of life, and their relations to each other. Here there is no restriction as to the use of scientific methods; there is wide range for free action by the hosts of observers required for the work. A sense of the relief which this implies, in contrast with the hampering restraints surrounding the earlier question, imparts to the words of Schmidt a more jubilant tone, as he says, "Between beginning and end, we naturalists may do as we please."[AV]

In this region it will be universally admitted that the development of species by selection is the conception which has gained greatest hold upon the scientific mind within recent times. Accordingly it seems better to begin with an outline of this theory, and of its history as developed by Mr. Darwin, keeping, however, steadily in view the range of problem with which the theory has to deal.

As already remarked the origin of life is a problem quite distinct, and the theory of selection does not entangle itself by maintaining origin of life by development from unorganized matter. Mr. Darwin clearly guarded himself against responsibility for such a conception of its origin.[AW] Restricting thus far, we have to keep in view the vast range of the problem demanding scientific explanation.

Animal life manifests itself by spontaneous movement,--movement from within the living organism, in contrast with movement caused by energy applied from without. This holds true of every living germ, from which a mature animal form may be developed. This is the test of the presence of life under the microscope in minute germinal structures otherwise incapable of observation. In its lowest known form life appears in a minute vessel containing so much nourishment, which is within a nucleus or vital centre from which movement originates.[AX] This depends for its development on external conditions such as heat and moisture.[AY] Advance in the scale is connected with greater complexity in the organism. As we ascend, separate organs appear, fulfilling distinct functions, and controlled by means of a nerve system whose ramifications are according to the intricacy of the organism. The appearance of such a nerve system implies sensibility and motor activity, provision for an _experience_ more or less varied, and _movement_ in some measure according with it, or adapted to it. From a nerve system consisting of a centre and a few fibres, we gradually ascend, until in the higher vertebrate orders, we find a vast system of nerves harmonized and governed from a grand centre or terminus constituting the brain.[AZ] With the steadily advancing complexity of nerve system, there is great diversity in the orders of animals, in the variety of actions of which they are capable, in adaptation to different conditions of life, and in the modes in which they obtain subsistence. The scientific problem is--How far can we account for all this complex system of things by the action of natural causes?

As we are here specially concerned with ruling conceptions, and only indirectly with details, the relations of the animal and vegetable kingdoms may be passed, with the acknowledgment that the two are obviously distinct, and yet that the vegetable very nearly merges into the animal at certain points, as illustrated by sensibility, if not by locomotion. So may we waive discussion of the classification of animals, which involves important points closely connected with the main question. Allowing that the wonderful diversity in animal organization, may admit of different modes of classification; and yet granting that the structure of the animal economy in all its forms proceeds on common principles, which must lead to practical agreement as to modes of classification; we deal with the single question as to the natural causes serving to explain different orders.

Mr. Darwin's suggestion, largely supported by evidence from many quarters, and now commanding a very general support is, that all this diversity may be regarded as the product of a long process of development. This theory takes the whole orders of existence into one sweep. The lowest type of animal life presents to view the beginning of a protracted history; the highest order of animate existence indicates the stage of advance at which we observe things at the present period. For such a theory the history of individual development belonging to whatever order, and the history of distinct orders as indicating improvement and deviation of whatever aspect, present evidence of special value. The most important causes relied upon as contributing to the formation of a scientific theory may be presented under these four heads--(1) The action of external causes as provided for by environment; (2) power of adaptability within each organism, providing for changes according to requirement from without, which may be described as "adaptive changes of structure;" (3) "the struggle for existence," in accordance with which the strongest gain the mastery and consequent advantage in obtaining the means of subsistence; and (4) "natural selection" among the sexes, giving to the offspring all advantages according to the laws of hereditary descent.