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constructed on one simple model; when we observe the precise order in which they disappear, exactly in accordance with the destined difference of function in the different species; when we trace the undeviating scheme on which the new modifications are respectively super-induced ; when we regard the determinate scale, according to which the whole process is unalterably carried on;—then we shall be urged with an increasing and accumulating force of conviction, to the conclusion that all this arrangement, however apparently complex, is, in reality, an astonishing instance of conformity to laws of the most recondite simplicity: that every step in the process, however apparently superfluous, is in strict accordance with a great principle of uniformity: that every stage in the transformation, however, in first appearance, destitute of direction to a purpose of utility, yet, if it answer no other, has its direct application in filling up a place in the universal harmony and incomparable unity of design, which pervades all organized nature. The very singularity of the provision, well considered, evinces the enlarged preservation of analogy: the very objection and difficulty of the case is converted into an evidence in favour of the argument from symmetry.
But this is not all: an extension of the same principle, nearly obvious when once it has been made known, enables us entirely to refute one of the most plausible objections, and remove one of the most formidable difficulties, which previously opposed itself as a positive exception to the harmony of design in the animal organization; the existence of cases of malformation. These are now understood, by the aid of the principle just adverted to, to be in fact, due not to any disordering interruption, not to any anomalous interfering cause, but simply to a deficiency in power to carry on the process of development; which is therefore merely arrested at an imperfect stage*
Proximate Causes compared with Fixed Laws.
The distinction which has been before drawn between physical and moral causation, and the relation of cause and effect, may tend, in no small degree, to remove a difficulty sometimes felt in the estimate of the proofs of creative wisdom and power supplied by the contemplation of organized life as compared with those derived from the study of the heavenly bodies. In the former case, the production of animal and vegetable life is observed to be always in connexion with a proximate material cause. In the latter we can conceive no material cause of the existence and motions of the planetary system. Hence it has been noticed that the former class of
* For an explanation of these cases (of which my limits will not allow the insertion,) the reader is referred to the same Introductory Lecture, p. 21.
phenomena do not furnish (to some minds at least,) the same conclusive evidence of a Deity as the latter *
Now when the nature of physical or material causes is distinctly understood according to the view we have here taken of it, it becomes evident that the material or physical agency which is referred to in the production of organized life, is nothing more than the series of laws to which we are able to reduce those processes of nature. We trace an invariable course of sequence and dependence of one : phenomenon or effect, upon another of a more general kind. We can follow up these trains of consequence through a considerable number of steps, and thus perceive a connected series of laws impressed upon the functions of material and organized beings. In the case of the heavenly bodies we cannot do this, at least with reference to the origination of their motions, or adjustment of their masses and distances. The difference, then, is solely that we can trace a longer series and a more complicated system of physical laws in the one case than in the other; and therein it would seem to follow a greater rather than a less manifestation of design and intelligence in the former case. In neither do we arrive at any efficient causation or moral agency but by carefully establishing the material indications of it; and it is solely from the adjustment of physical laws
* See Dr. Turton's Natural Theology, p. 54.
that we are able to trace those indications. The material proximate causes (as they are termed,) of the production of organized life are causes of a different kind from that moral causation which, in the imposition of laws on matter, and in calling that matter into its existing combinations, we recognise as creative power.
Evidences of Creation. Just and sober inductive science, applied to the examination of the actual structure of the earth's crust, enables us with satisfaction and certainty to trace the changes which have taken place on the surface of a globe possessing the same nature as the existing earth, and in the structure and habits of organized beings analogous to those now inhabiting the world. It investigates the alterations which have been effected by physical agents resembling those now in operation, and in accordance with general laws the same as those now recognised in the economy of nature.
But it does not, and cannot rise to the disclosure of what occurred under a different state of things, or owing to the action of causes of a different order from those now discovered by physical research. It cannot show a chaos, or trace the evolution of a world out of it. It cannot reason upon a supposed state of universal confusion and ruin, and the imme* diate reduction of it into order and arrangement.
It can investigate the changes of things, but not their origin; in a word, sound geology will never aspire to the character of cosmogony.
Geology is, indeed, pre-eminently distinguished from other branches of physical science in this, that while they teach us only the existing order of nature, this carries us back in time, and shows a period when the present races of organized beings did not exist; and by consequence, establishes the fact of a creation, that is, more properly, of a series of creations; and these manifestly not brought about at any one marked period, or extending to all animated nature at once, but by the slow and gradual introduction of each new species as the older disappeared.
The successive strata are the sepulchres of successive races of organized beings, differing more or less from existing species; and those of the least antiquity containing extinct species, co-existent with those now tenanting the globe, and bearing decisive evidences of progressive, local, gradual deposition and elevation. The marks of sudden violence, indeed, are occasionally seen in all formations; but their occurrence is the exception, not the rule; and in its most extreme cases, always limited to a narrow local extent. No one simultaneous universal change has ever taken place on the surface of the globe; but all effects, however great, have been accomplished by a series of local and partial changes; and even where we may be left to conjecture as to the violence or suddenness of those changes with respect