It is equally true that the habit of making such assumptions, even tacitly, is difficult to avoid. Because when proofs have already largely accumulated, we are of course prepossessed with the conclusion which we suppose the further instances must also substantiate. But when our avowed object is the exact discrimination of evidence as such, and the strict analysis of our impressions into their logical elements, the distinctions must be studiously kept in view.

The illustration of the man on crutches has been blamed as idle and unbecoming. It does not appear to me deserving of censure in this way, though I think it inapplicable, as being an argument upon an isolated and accidental case; the essence of such reasoning consists in its extension to entire species and classes of beings in their natural relations. At all events, whatever may be thought of the particular illustration, the same remark must be still applied with regard to any assumption of designing moral agency in the adaptation.

Let us, in such reasoning, only bear in mind these obvious distinctions. Let us not allow physical investigation to borrow from natural theology, if it is to furnish the very means of support to divine truth. Let not natural theology be made to minister to science, if science is to be the handmaid to natural theology.

In physical laws we must keep clear of assuming moral causation. But the general laws and analogies

already established may fairly be taken as our guides to others yet to be made out. They, indeed, must be so appealed to; for, as we endeavoured to show at the outset, they are recognised, and bear an essential part, even in the strictest logical analysis of inductive reasoning*.

In the particular instance, then, of the physiological topics referred to, we may fairly adopt (as the evidence may seem to warrant,) either the principle of "analogues," or of the "use of organs," (this latter being carefully distinguished in meaning from any idea of moral causation.) But these or other equivalent physiological theories must be taken simply as such, and barely as far as they are warranted by inductive laws; and in this way they may be most correctly adopted, and even become indispensable as our guides in considering any new case, or carrying on any further research.

Comparison of Arguments from Order and from Mechanism.

THE examination of the question last referred to may suggest some further reflections not unimportant with reference to the evidences of natural theology.

The two theories of comparative physiology to which we have been referring, and which have been

* See Section I., page 25, and note.

⚫ considered as so much opposed, especially in their bearing upon the conclusions of natural theology, do not, upon closer examination, appear to present anything really at variance. Without pretending to form an opinion on their respective merits, considered physiologically, I will merely observe this much: Both systems tend equally to establish the existence of profoundly adjusted order and uniformity in nature, though of somewhat different kinds. The one system contemplates the entire range of animated beings, and unveils to the well-directed eye of the physiologist the most marvellous preservation of exact analogy, even throughout the most apparently trackless mazes of dissimilarity. other, without taking this wide range, yet establishes the same truth, within more limited and detached portions of the field of inquiry, and within those several limited portions enlarges greatly our perception of the combination of adjustments in which the same great principles are manifested.

The

The one theory dwells on the relations and adaptations of whole classes and orders of animated structures to each other; the other, on the relations and adaptations of the several parts of one animated structure to each other, and to the purpose of the preservation and well-being of the whole. The one leads us to consider the more abstract analogies which connect together the various parts of animated nature by general laws; the other, the more practical relations and mutual subserviency of the parts of

organic structures to the purposes of animal existence. The one shows a vast and perfect composition, an elaborate and systematic design, presented to our contemplation; the other, a profoundly ingenious and complicated machine set in action.

Now, if we consider the bearing of these views on natural theology, it must, I think, be admitted that they both, though in somewhat different ways, tend equally to substantiate the great inference of design. In the universal preservation of systematic order, susceptible of exact classification by pervading analogies, there is just the same indication of design and intelligence as in the adaptation and adjustment of the parts of any individual machinery to an end.

An elaborate design of art, a well-proportioned edifice, a magnificent painting, though addressing themselves solely to our contemplation in their silent and immovable proportions, are surely quite as forcible manifestations of intellect and genius, as the most skilfully contrived piece of machinery in incessant activity, fabricating the most useful productions.

Either way, then, in the study of nature there is an equally clear manifestation of that infinite intelligence, which, after the inductive examination of the laws or adjustments in either case, we are directly led to acknowledge as the irresistible conclusion. And as this is the case with either species of investigation singly, so will it be more pre-eminently true when both are pursued jointly, as they assuredly may be, without the smallest detriment to each other, or

confusion of first principles, provided only we keep strictly to the simplest rule of all just reasoning, and do not confound our final conclusion with our first

assumption.

The highest philosophy is most disposed to cherish a readiness to perceive and admit the fair indications of design and intelligence, in whatever form they may present themselves; and there is a wider expansion given to our views when we thus include the contemplation of order and symmetry, (even though we perceive not their end or object,) in our notion of design. In such considerations we may find the loftiest exercise of truly philosophical reflections; we shall realize the highest aim of scientific speculation; and shall recognise the truth of the remark so forcibly expressed by Dugald Stewart :-"There is a certain character, or style (if I may use the expression,) in the operations of Divine Wisdom; something which everywhere announces, amidst an infinite variety of detail, an inimitable unity and harmony of design; and in the perception of which philosophical sagacity and genius seem chiefly to consist."

Example:-Botanical Symmetry.

THERE are few branches of science from which we learn more decisive indications of that wonderful symmetry and order which exist in the disposition

Philosophy of Mind, ii. 418.