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even to transform them into evidences of the existence of this very order."
I will not injure the force and beauty of this illustration by any comment. The conclusion appears to me irresistible, that symmetry of arrangement is as decided a proof of design as adjustment of mechanism-beauty and harmony as clear indications of mind, as combination of mechanical action.
Examples from Physiology.
FEW parts of the organized body were more completely involved in obscurity as to their nature and functions than the nervous system; until of late years, by the united labours of Sir Charles Bell, M. Magendie, and Mr. Herbert Mayo, a valuable light has been shed upon the subject.
All parts of the body over which we have any control, are found to be furnished with two distinct sets of nerves. Every part has also, as we well know, two distinct powers or functions, one passive, or that of sensation: the other active, or that of voluntary motion. Of the two sets of nerves one invariably gives the first power: the other the second.
This recondite distinction of use and properties, so undeviating in the midst of the greatest apparent complexity, is surely a striking instance of the most beautiful harmony between the distribution of the organs and the corresponding functions. Though we
perceive no mechanical principle of contrivance, nor (in the ordinary sense) any reason for the twofold system of nerves.
But these researches have been carried further:
at first sight nothing would seem more devoid of order or method than the arrangement of the origins of the respective systems of nerves. Mr. H. Mayo*, however, has succeeded in reducing the apparent confusion to a simple system. He has made out the general law of distribution, that the nerves of motion have their roots in the same part or segment of the nervous centre as the corresponding and accompanying nerves of sensation.
The same physiologist has pursued the subject more recently, and has deduced many curious results, especially involving the confirmation of the profound anticipations of Dr. Whytt (1768); which are remarkable as tending to simplify and reduce to a common principle, the instances of many motions and affections, which have been regarded as involuntary; of which we seem unconscious; but which yet are really results of volition, though overlooked from habit. The consideration of probability and analogy derived from the simplicity of nature, was here the guiding principle which led the author to his inferences; and which is so beautifully confirmed by them.
* Outlines of Physiology, 4th edit. p. 263; and On the Powers of the Roots of the Nerves, &c., London, 1837, p. 17.
+ Ibid. P. 21.
The cases last referred to afford good examples of a simplification of principle, which may be fairly urged as a proof of Presiding Intelligence in the arrangement of the organized body, though we see nothing but the indications of this symmetry and order, and no positive perception of a use or end answered. To look only to such purposes, or practical contrivances, is to take far too narrow a view of final causes. We should learn to trace design equally, perhaps even more clearly, in cases where we perceive no end or practical design, but where the influence of ordaining intelligence is displayed solely in the continually increasing simplicity of principle and symmetry of arrangement, which are constantly opening upon us in every successive advance of discovery.
It has been admirably observed by the distinguished physiologist just referred to, "As philosophy advances the properties of matter are perpetually found to be fewer and simpler; which the creative wisdom so combines and directs as to produce the most diversified, and, at first sight, opposite results*." The disclosure of such a principle alone seems to me to constitute the highest kind of proof of presiding and ordaining Intelligence. I have above referred to some instances in support of it; but I must here add one more case, which places the argument in a peculiarly striking point of view, derived from the
* Introductory Lecture at King's College, 1834, p. 16.
researches of modern physiology; and which I cannot express better than in the words of the same author:
"One common commencement is there for the development of all the families of vertebral animals. There is a period after its commencement, when the frame in outline being already distinct, the class even of the individual is indistinguishable, whether it be fish, reptile, bird, mammiferous animal, or even man. For a time, these all march parallel, alike in all things, the highest not differing from the lowest. For example: the fish, the lowest in the scale, is formed to breathe the waters; for this purpose, in its throat there must be openings made, to give passage to the water through its gills. These openings are called branchial apertures. The reptile has no need of these openings; but they are formed in it. In the bird they would serve no use; but they are there. In the mammiferous animal again, in man, they are useless, but they are still present. Respiratory apertures in the neck, with a single heart, and a corresponding distribution of the aorta, form the early undistinguished and undistinguishing type stamped on the whole range of vertebrata.
"But now a difference begins. This character of organization is to be permanent in fish. In fish, therefore, it now expands and amplifies itself. At the corresponding period, in the higher animals, it
* Ibid. p. 20.
fades and disappears; shrinking, while a higher order of organization supersedes it, and parts are developed which in the fish appear not. This law holds throughout the economy. There is one common type for the brain at its first production, which remains permanent in the lowest tribes, but is improved upon by fresh developments in each above. Thus the brain of man at first resembles that of a fish, then of a reptile and bird: finally, it becomes the mammiferous brain, then human."
On contemplating so truly astonishing a train of development as is here unfolded, the reflection which presents itself to the mind may, in the first instance, be very different from that which is induced on a more enlarged consideration of the
In the gradual stages of the process here unveiled, we perceive organs bestowed apparently without discrimination as to the future destiny of the creature: adapted in many to no perceptible end; in fact, positively useless and superfluous. All notion of final causes seems excluded; and all idea of adjustment to a purpose, violated. Even the suppression of a useless organ, and the substitution or super-induction of one which is useful, seems a circuitous and unnecessarily complex process of obtaining the end ultimately accomplished.
But when we look at the regularity of the system on which all this is planned; when we consider that these useless or abortive organs are, in all cases,