made on as firm ground, as when they trod their common road together. No matter how extended the series may be, if each link is a direct deduction from the preceding, the first will be no more sound and irrefragable in its demonstration than the hundredth or the thousandth. It is true, that because of human infirmity, the longer process will be more liable to human mistake and error. But this only proves the necessity of great circumspection and care in the investigation; not at all that when it is rightly made, the last step is not as safe and sure as the first. If the whole chain is correctly put together, it will hold fast to any demonstration, however remote from the beginning. The short deduction " Cogito, ergo sum," is no more certain than the most remote human duty, deduced from the existence and attributes of God and his relation to his creatures. While natural theology does carry its deductions farther out than natural philosophy, it is not therefore the less certain of their correctness. The end is inferred no more surely from the adaptation, than the design compels the deduction of the existence of the GREAT DESIGNER.

With these remarks in view, we shall adduce a number of examples common both to philosophical science and natural theology, for the purpose of showing how completely both are identified in all which renders their deductions sound and conclusive. In doing this, we shall follow somewhat in the order of Lord Brougham, but without confining ourselves either to his facts or illustrations. We shall avoid also, as we have hitherto done, the technical terms 'psychological," "ontology," "deontology," etc., as more appropriate to a strictly scientific treatise, and endeavor to give the ideas for which they stand in the ordinary language of common life.

An examination of the structure of the eye, in all the complicated parts of its formation, leads directly to the knowledge of the fact, that it is in perfect adaptation to the properties of light. This fact was obvious before many of the properties now known to belong to light had been discovered. A plain man now, as in any former age, without any philosophical understanding of the subject, has sufficient knowledge of the fact, to admit that the eye and the light are fitted to each other. But when Newton discovered the fact of the different degrees of refrangibility in light, and thus a new and interesting property of it had come to the knowledge of the world, it was also at once seen, that the eye, by its combined lenses of different material, was fitted to this newly discovered property; and in full accordance therewith, was made to throw the image distinctly upon the retina, and thus secure clearness of vision. Mr. Dolland, the celebrated optical-instrument maker in London, subsequently found, that different substances possessed the quality of scattering the rays of light in different degrees. By compounding these different substances in a certain proportion,

object-glasses of far greater perfection than had before been used, were constructed. But it was also manifest, upon the first observation, that the eye had this improvement in a far more perfect manner, than all the compounds of human skill could effect. Thus the general fact, of the mutual adaptations of the eye and light, always admitted, is traced out in its more minute particulars, as science discovers more of their respective properties. Natural philosophy gathers up these facts, finding new properties, tracing analogies and adaptations, following them out to their final causes, and looks down upon the work delighted; wondering at the beauty of the organ, the perfect mutual relations, and the complete attainment of the end,-the mysterious power of vision. No one questions the reality of its facts, or the soundness of its deductions.

But while philosophy is thus absorbed in the admiration of its own discoveries, natural theology has gone over the same ground, gathered up the same facts, and traced the same nice adaptations, and then drawn the incontrovertible deduction, that all this must have been well known to the Maker of the eye, before it had been discovered by the investigations of human science; that such marks of skilful design evidently bespeak the existence of a supreme, intelligent, first cause; and thus having found him, stands before the throne of the great Eternal, humble and adoring. We might enlarge, and show the adaptations of the eye in its different modifications, to every varied condition in which its use is required. The mole that burrows in the earth, the fish inhabiting the denser element of water, and the eagle soaring into the heavens, with a sight so piercing, that he can discern his prey on the surface of the distant globe beneath him, all have peculiarities of structure and furniture in the eye, which fits it for its destined place of operation. Thus, while natural philosophy gathers its facts and deduces the ends to which they are subservient, natural theology, from the same materials, and by the same process carried out, discovers also the existence and attributes of their great Author.

A quill from the wing of a fowl, when minutely examined, is an interesting instance of nice adaptation to the end for which it is to be used. The barrel, or stem, is of a peculiar, firm texture, that it may possess sufficient strength to sustain the weight of the body and force of the stroke in flying, and yet hollow and light that it may not itself be a burden. The continuance of the stalk, as it runs off into a more porous and homogeneous substance, preserves the same adaptation, and yet is fitted to give place and nourishment to the filaments which arise in continuation on each side of it. These filaments are arranged in separate lamina, the broadest surfaces of which lie upon each other, so that the force which acts upon them in flying comes upon their edges, and thus meeting them in the direction of their plane, receives the resist

ance of their whole substance. These filaments, it is obvious, must, in some measure, be bound together, or they would be as insufficient for the purposes of flying, as the scattered threads of down upon the feathers of the ostrich. Any glutinous substance, would be subject to injury from the constant exposure to weather, or soiled and loaded from the dust and particles of matter with which it would come in contact. To accomplish this purpose therefore, in the most perfect manner, from the edges of the various filaments, as examined through a microscope, are seen little sets of fibrils or teeth thrown off upon one side, which are fitted by opposite clasps to shut into, or overlock those that are thrown off by the next on its adjoining side, and thus hold themselves firmly together. Each quill in the wing is then so placed, that the filaments of its broadest side lie over those on the narrowest side of its fellow next in succession, the greater strength of the one thus supporting the weaker side of the other; while that in turn is the more expanded to oppose the greater surface to the air, upon which it is to act in sustaining the body upon its bosom. If to all this we add the exact points in which the wings are attached to the body, to sustain it in equilibrium, the formation of the joints for the peculiarity of its rotary motion in flying, and the position and action of the muscles, in exact conformity with the principle of antagonist forces, in which it is to strike the resisting medium of the atmosphere, we find as true a system of the nicest adaptations, to a particular and important purpose, as can well be conceived.

The circulation of the blood in the animal system, the discovery of which has immortalized the name of Harvey, though too complicated to admit here of a full description, may nevertheless bear a general reference. The heart, which is the great laboring engine in performing the work, is a hollow and muscular organ of a conical shape, divided into four compartments, the two larger termed ventricles, and the two smaller auricles. The former send forth the blood into the arteries, the latter receive it from the veins. In the arteries are numerous valves, which all close toward the heart; the veins also have numerous valves which all close the other way, against the passage from the heart. A contraction of the heart, sends the blood from the right ventricle, through the pulmonary arteries, into the lungs. There, by a most wonderful adaptation of structure, the blood receives its vital properties from the air which has been inhaled, and gives off its noxious qualities, which are exhaled at the next respiration. From the lungs it returns by the pulmonary veins again to the heart, and enters the left auricle. It then begins its more general circulation. The left ventricle sends the blood into a large artery, called the aorta, branches of which go upwards to the head and arms, and other branches along the inside of the

spine to the lower extremities. The minute extremities of the arteries, by a change in the direction of their valves, become veins through which the blood returns toward the heart, and all uniting in one main trunk, called the vena cava, the blood is again poured into the heart at the right auricle, and thus completes the circulation through the whole system. The heart contracts about 4000 times an hour, sending off about one ounce of blood at each stroke, or about 250 pounds in an hour. If the blood in the human body be estimated at twenty-five pounds, the whole, at the above ratio, would pass through the general circulation once in six minutes, or ten times an hour. Nothing can exceed the wondrous adaptation here displayed to keep the vital stream in constant motion. It was the observation of this adaptation, which led to the discovery of the fact. When Mr. Boyle inquired of Harvey, "What induced him to think of the circulation of the blood?" he answered: "that when he took notice that the valves in the veins were so placed that they gave free passage to the blood toward the heart, but opposed the passage of the veinal blood the contrary way, he was incited to imagine, that so provident a cause as nature had not so placed so many valves without design, and no design seemed more probable, than that since the blood could not well, because of the interposing valves, be sent by the veins to the limbs, it should be sent through the arteries and return through the veins whose valves did not oppose its course that way." On the principle, that "nature" was "a provident cause," and did not act without design," Harvey inferred, from facts which he saw, the circulation of the blood. Certainly it is no less philosophical with natural theology, to infer, from the circulation of the blood and the minute contrivances to effect it, the existence of this "provident cause."

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The following is another example, in the words of Lord Brougham:

When a bird's egg is examined, it is found to consist of three parts; the chick, the yelk in which the chick is placed, and the white in which the yelk swims. The yelk is lighter than the white, and it is attached to it at two points, joined by a line or rather plane below the center of gravity of the yelk. From this arrangement it must follow, that the chick is always uppermost, roll the egg how you will; consequently the chick is always kept nearest to the breast or belly of the mother, while she is sitting. Suppose then that any one acquainted with the laws of motion, had to contrive things so as to secure this position for the little speck or sac in question, in order to its receiving the necessary heat from the hen,-could he proceed otherwise than by placing it in the lighter liquid, and suspending that liquid in the heavier, so that its center of gravity should be above the line or plane of suspension? Assuredly not; for in no other way could this purpose be VOL. VIII. 25

accomplished. This position is attained by a strict induction ;* it is supported by the same kind of evidence on which all physical truths rest. But it leads by a single step to another truth in natural theology, that the egg must have been formed by some hand skillful in mechanism, and acting under the knowledge of dynamics.' pp. 25, 26.

The human hand is another striking instance of the complicated adaptation of means to an end, but which we have not space to describe. We refer to the learned work in the Bridgewater Treatises, on this subject, by Sir Chas. Bell, and also to a notice of this work on our pages. Ch. Spec. for March, 1834. Art. III.

In the solar system, we see the planets revolving in orbits which are not complete circles, but more or less flattened into ellipses. While the primaries are rolling onward, in several instances they are also carrying along their secondaries by a double motion,-around their primaries, and with them around their great center the sun,—and in all there is still another motion in their individual rotation upon their axis. These complicated but regular movements, prove intelligence and wisdom as the source of their harmony. But there is another peculiarity observed in their movements, that deserves special attention. There is a constant and uniform alteration of their orbits in one way up to a given point, which then becomes an inverse alteration down to a given point, and never passing beyond the goal on either side. Philosophy inferred, that this was necessary to the counteraction of disturbing influences from unequal attractions, and thus to the permanency of the system. This inference of philosophy became demonstration by the integral calculus. But surely the deduction of philosophy in this case ought not to be considered as more sound and legitimate than that of natural theology, which, taking all these facts in their harmony, infers directly from this universe of sublimities the existence of its almighty Architect.

We adduce only one more example from the material world. Philosophy sometimes seizes upon the mere fragment of some former entire existence, and through the line of known relations and dependencies, by a series of deductions, comes out at last to the complete knowledge of that entire existence, of which at first it had only some of its scattered relics as the data. Geology and especially comparative anatomy, as followed out by Baron Cuvier, Prof. Buckland, and others, throws many such a startling fact before its disciples. In a cave, or in a ruptured strata, or perhaps amid the debris of some wild region, a decayed and partial fragment of the skeleton of an unknown animal is discovered; perhaps but two or three broken bones are gathered up from

* The same erroneous application of the phrase as that before mentioned.