gist, water is constantly labouring to reduce all the inequalities of the earth to a single level; while fire, with its volcanic action, is equally busy in restoring those inequalities, by throwing up matter to the surface, and in various ways disturbing the crust of the globe.169 And as the beauty of the material world mainly depends on that irregularity of aspect, without which scenery would have presented no variety of form, and but little variety of colour, we shall, I think, not be guilty of too refined a subtlety, if we say that fire, by saving us from the monotony to which water would have condemned us, has been the remote cause of that development of the imagination which has given us our poetry, our painting, and our sculpture, and has thereby not only wonderfully increased the pleasures of life, but has imparted to the human mind a completeness of function, to which, in the absence of such a stimulus, it could not have attained.

When geologists began to study the laws according to which fire and water had altered the structure of the earth, two different courses were open to them, namely, the inductive and the deductive. The deductive plan was to compute the probable consequences of fire and water, by reasoning from the sciences of thermotics and hydrodynamics; tracking each element by an independent line of argument, and afterwards coördinating into a single scheme the results which had been separately obtained. It would then only remain to inquire, how far this imaginary scheme harmonized with the actual state of things; and if the discrepancy between the ideal and

169"The great agents of change in the inorganic world may be divided into two principal classes, the aqueous and the igneous. To the aqueous belong rain, rivers, torrents, springs, currents, and tides; to the igneous, volcanos and earthquakes. Both these classes are instruments of decay as well as of reproduction; but they may also be regarded as antagonist forces. For the aqueous agents are incessantly labouring to reduce the inequalities of the earth's surface to a level; while the igneous are equally active in restoring the unevenness of the external crust, partly by heaping up new matter in certain localities, and partly by depressing one portion, and forcing out another, of the earth's envelope." Lyell's Principles of Geology, 9th edit., London, 1853, p. 198.

the actual were not greater than might fairly be expected from the perturbations produced by other causes, the ratiocination would be complete, and geology would, in its inorganic department, become à deductive science. That our knowledge is ripe for such a process, I am far, indeed, from supposing; but this is the path which a deductive mind would take, so far as it was able. On the other hand, an inductive mind, instead of beginning with fire and water, would begin with the effects which fire and water had produced, and would first study these two agents, not in their own separate sciences, but in their united action as exhibited on the crust of the earth. An inquirer of this sort would assume, that the best way of arriving at truth would be to proceed from effects to causes, observing what had actually happened, and rising from the complex results up to a knowledge of the simple agents, by whose power the results had been brought

about.

If the reader has followed the train of thought which I have endeavoured to establish in this chapter, and in part of the preceding volume, he will be prepared to expect that when, in the latter half of the eighteenth century, geology was first seriously studied, the inductive plan of proceeding from effects to causes, became the favourite one in England; while the deductive plan of proceeding from causes to effects, was adopted in Scotland and in Germany. And such was really the case. It is generally admitted, that, in England, scientific geology owes its origin to William Smith, whose mind was singularly averse to system, and who, believing that the best way of understanding former causes was to study present effects, occupied himself, between the years 1790 and 1815, in a laborious examination of different strata.170

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170 Dr. Whewell, comparing him with his great German contemporary, Werner, says, "In the German, considering him as a geologist, the ideal element predominated." Of a very different temper and character was William Smith. No literary cultivation of his youth awoke in him the speculative love of symmetry and system; but a singular clearness and precision of the classifying power, which he possessed as a native talent, was exercised and developed by exactly those geological facts among which his

In 1815, he, after traversing the whole of England on foot, published the first complete geological map which ever appeared, and thus took the first great step towards accumulating the materials for an inductive generalization.171 In 1807, and, therefore, before he had brought his arduous task to an end, there was formed in London the Geological Society, the express object of which, we are assured, was, to observe the condition of the earth, but by no means to generalize the causes which had produced that condition. 172 The resolution was, perhaps, a wise one. At all events, it was highly characteristic of the sober and patient spirit of the English intellect. With what energy and unsparing toil it has been executed, and how the most eminent members of the Geological Society have, in the pursuit of truth, not only explored every part of Europe, but examined the shell of the earth in America and in Northern Asia, is well known to all who are interested in these matters; nor can it be denied, that the great works of Lyell and Murchison prove that the men who are capable of such laborious enterprises, are also capable of the still more difficult achievement of generalizing their facts and refining them into ideas. They did not go as mere ob

philosophical task lay." "We see great vividness of thought and activity of mind, unfolding itself exactly in proportion to the facts with which it had to deal." "He dates his attempts to discriminate and connect strata from the year 1790." Whewell's History of the Inductive Sciences, London, 1847, vol. iii. pp. 562-564.

171 The execution of his map was completed in 1815, and remains a lasting monument of original talent and extraordinary perseverance; for he had explored the whole country on foot without the guidance of previous observers, or the aid of fellow-labourers, and had succeeded in throwing into natural divisions the whole complicated series of British rocks." Lyell's Principles of Geology, p. 58. Geological maps of parts of England had, however, been published before 1815. See Conybeare on Geology, in Second Report of the British Association, p. 373.

1:2A great body of new data were required; and the Geological Society of London, founded in 1807, conduced greatly to the attainment of this desirable end. To multiply and record observations, and patiently to await the result at some future period, was the object proposed by them; and it was their favourite maxim, that the time was not yet come for a general system of geology, but that all must be content for many years to be exclusively engaged in furnishing materials for future generalizations." Lyell's Principles of Geology, p. 59. Compare Richardson's Geology, 1851, p. 40.

servers, but they went with the noble object of making their observations subservient to a discovery of the laws of nature. That was their aim; and all honour be to them for it. Still, it is evident, that their process is essentially inductive; it is a procedure from the observation of complex phenomena, up to the elements to which those phenomena are owing; it is, in other words, a study of natural effects, in order to learn the operation of natural causes.

Very different was the process in Germany and Scotland. In 1787, that is, only three years before William Smith began his labours, Werner, by his work on the classification of mountains, laid the foundation of the German school of geology.173 His influence was immense; and among his pupils we find the names of Mohs, Raumer, and Von Buch, and even that of Alexander Humboldt.174 But the geological theory which he propounded, depended entirely on a chain of argument from cause to effect. He assumed, that all the great changes through which the earth had passed, were due to the action of water. Taking this for granted, he reasoned deductively from premisses with which his knowledge of water supplied him. Without entering into details respecting his system, it is enough to say, that, according to it, there was originally one vast and primeval sea, which, in the course of time, deposited the primitive rocks. The base of all was granite; then gneiss; and others followed in their order. In the bosom of the water, which at first was tranquil, agitations gradually arose, which, destroying part of the earliest deposits, gave birth to new rocks, formed out of their ruins. The stratified thus succeeded to the unstratified, and something like variety was established. Then came another period, in which the face

173 Cuvier, in his Life of Werner, says (Biographie Universelle, vol. L. pp. 376, 377), "La connaissance des positions respectives des minéraux dans la croûte du globe, et ce que l'on peut en conclure relativement aux époques de leur origine, forment une autre branche de la science qu'il appelle Géognosie. Il en présenta les premières bases en 1787, dans un petit écrit intitulé Classification et description des montagnes."

174 Whewell's History of the Inductive Sciences, vol. iii. p. 567.

of the waters, instead of being merely agitated, was convulsed by tempests, and, amid their play and collision, life was generated, and plants and animals sprung into existence. The vast solitude was slowly peopled, the sea gradually retired; and a foundation was laid for that epoch, during which man entered the scene, bringing with him the rudiments of order and of social improvement. 175

These were the leading views of a system which, we must remember, exercised great sway in the scientific world, and won over to its side minds of considerable power. Erroneous and far-fetched though it was, it had the merit of calling attention to one of the two chief principles which have determined the present condition of our planet. It had the further merit of provoking a controversy, which was eminently serviceable to the interests of truth. For, the great enemy of knowledge is not error, but inertness. All that we want is discussion, and then we are sure to do well, no matter what our blunders may be. One error conflicts with another; each destroys its opponent, and truth is evolved. This is the course of the human mind, and it is from this point of view that the authors of new ideas, the proposers of new contrivances, and the originators of new heresies, are benefactors of their species. Whether they are right or wrong, is the least part of the question. They tend to excite the mind; they open up the faculties; they stimulate us to fresh inquiry; they place old subjects

175 Une mer universelle et tranquille dépose en grandes masses les roches primitives, roches nettement cristallisées, où domine d'abord la silice. Le granit fait la base de tout; au granit succède le gneiss, qui n'est qu'un granit commençant à se feuilleter." "Des agitations intes

tines du liquide détruisent une partie de ces premiers dépôts; de nouvelles roches se forment de leurs débris réunis par des cimens. C'est parmi ces tempêtes que naît la vie." "Les eaux, de nouveau tranquillisées, mais dont le contenu a changé, déposent des couches moins épaisses et plus variées, où les débris des corps vivans s'accumulent successivement dans un ordre non moins fixe que celui des roches qui les contiennent. Enfin, la dernière retraite des eaux répand sur le continent d'immenses alluvions de matières meubles, premiers siéges de la végétation, de la culture et de la sociabilité." Eloge de Werner, in Cuvier, Recueil des Eloges Historiques, vol. ii. pp. 321-323.