AuQ. 15, 1872] 



NATURE 



that which consists in the power of retaining and generalising 

 experiences. 



I have not introduced this subject with any idea of placing 

 before you even a summary of the ingenious arguments by which 

 these oppo^in^ doctrines have been respectively supported ; nor 

 should I have touched on the question at all, if I did not believe 

 that a means of reconcilement between them can be found in 

 the idea that tlie Intellectual Intuitioits of any one Generation are 

 the embodied Exterieiiees of the previous Race. For, as it appears 

 to me there has been a progressive improvement in the Think- 

 ing Pcu'cr of Man ; every product of the culture which has pre- 

 ceded serving to prepare the soil for yet more abundant harvests 

 in the future. 



Now as there can be no doubt of the Hereditary transmission 

 in Man of acquired constitutional peculiarities, which manifest 

 themselves alike in tendencies to Bodily and i\Iental disease, so 

 it seems equally certain tliat acquired mental habitudes often im- 

 press themselves on his organisation, with sufficient force and 

 permanence to occasion their transmission to the offspring as 

 tendencies to similar modes of thought. And thus, while all admit 

 that Knowledge cannot thus descend from one generaiion to 

 another, an increased aptitude for the acquirement, either of 

 knowledge generally, or of some particular kind of it, may be 

 thus inherited. These tendencies and aptitudes will acquire ad- 

 ditional strength, expansion, and permanance, in each new 

 generation, from their habitual exercise upon the materials sup- 

 plied by a continually enlarged experience ; and thus the acquired 

 habitudes produced by the Intellectual culture of ages, will be- 

 come "a second nature " to every one who inherits them.* 



We have an illustration of this progress in the fact of con- 

 tinual occurrence, that conceptions which prove inadmissable to 

 the minds of one generation, in consequence either of their 

 want of intellectual power to apprehend them, or of their pre- 

 occupation by older habits of thought, subsequently find a uni- 

 versal acceptance, and even come to be approved as *' self- 

 evident." Thus the First Law of Motion, divined by the genius 

 of Newton, though opposed by many Philosophers of his 

 time as contrary to all experience, is now accepted 

 by common consent, not merely as a legitimate inference from 

 Experiment, but as the expression of a necessary and universal 

 truth ; and the same Axiomatic value is extended to the still 

 more general doctrine, that Energy of any kind, whether mani- 

 fested in the "molar" motion of masses, or consisting in the 

 "molecular" motion of atoms, must continue under some form 

 or other without abatement or decay ; what all admit in regard 

 to the indestructibility ol Matter, being accepted as no less 

 true of Force, namely, that as ex nihilo nil fit, so nil fit 

 ad nihiium t 



But, it may be urged, the very conception of these and similar 

 great truths is in itself a typical example t>f Intuition. The men 

 who divined and enunciated them stand out above their fellows, 

 as possessed of a Genius which could not only combine but 

 create, of an Insight which could clearly discern what Reason 

 could but dimly shadow forth. Granlmg this freely, I think it 

 may be shown that the Intuitions of individual Genius are but 

 specially exalted forms of endowments which are the general 

 property of the Race at the time, and which have come to be so 

 in virtue of its whole previous culture. Who, for example, 

 could refuse to the marvellous aptitude for perceiving the rela- 

 tions of Numbers, v\hich displayed itself in the untutored boy- 

 hood of George Bidder and Zerah Colburn, the title of an 

 Intuitive gift ? But who, on the other hand, can believe that a 

 Bidder or a Colburn could suddenly arise in a race of Savages 



* I am glad to be able to append the following extract from a letter which 

 Mr. John Mill, the great Waster of the Experimental School, was good 

 enough to write to me a few months since, with reference to the attempt I 

 had made to place " Common Sense " upon this basis (Contemporary I\c- 

 ve-JD, Feb. 1872) :— " When stales of mind in no respect inate or instinctive 

 have been frequently repeated, the mind acquires, as is proved by the power 

 of Habit, a greatly increased facility of passing into those states ; and this 

 increased facility must be owing to some change of a physical character in 

 the organic action of the Brain. There is also considerable evidence that 

 such acquired ficilities of passing into certain modes of cerebral action can 

 in many cases be transmitted, more or less completely, by inheritance. 1 he 

 limits of this power of transmission, and the conOitions on which it depends, 

 are a subject now fairly before the scientific world ; and we shall doubtless 

 in time know much more about them than we do now. But so far as my 

 imperfect knowledge of the subject qualities me to have an opinion, I take 

 much the same view of it that you do, at least in principle." 



t This is the form in which the doctrine now known as that of the " Con- 

 ser\'ation of Energy *' was enunciated by Dr. Mayer, in the very remarkable 

 Essay published by him in 1845, entilled "Die organische Bewegung in 

 ihrcm Zus ammenhangc mit dem Stoffwechsel." 



who cannot count five? Or, again, in the history of the very 

 earliest days of Mozart, w'ho cannot fail to recognise the dawn 

 of that glorious Genius, whose brilliant but brief career left its 

 imperi.shable impress on the Art it enriched ? But who would 

 be bold enough to affirm that an infant Mozart could be born 

 amongst a tribe whose only musical instrument is a tom-tom 

 whose only song is a monotonous chant ? 



Again, by tracing the gradual genesis of some of those Ideas 

 which we now accept as "self-evident " — such, for example, as 

 that of the " Uniformity of Nature" — we are able to recognise 

 them as the expressions of certain Intellectual tendencies, which 

 have progressively augmented in force in successive generations, 

 and now manifest themselves as Mental Instincts that penetrate 

 and direct our ordinary course of Thought. Such Instincts con- 

 stitule a precious heritage, which has been transmitted to»us with 

 ever-increasing value through the long succession of preceding 

 generations ; and which it is for us to transmit to those who 

 shall come after us, with all that further increase which our 

 higher Culture and wider range of Knowledge can impart. 



And now, having studied the working action of the Human 

 Intellect in the Scientific Interpretation of Nature, we shall 

 examine the general character of its products ; and the first of 

 these with which we shall deal is our conception of Matter and 

 of its relation to Force. 



The Psychologist of the present day views Matter entirely 

 through the light of his own Consciousness : his idea of Matter 

 in the abstract being that it is a " something " which has a 

 permanent power of exciting Sensations ; his idea of any 

 " property " of Matter being the mental representation of som.e 

 kind of sensory impression he has received from it ; and his idea 

 of any particular kind of Matter being the representation of the 

 whole aggregate of the Sense-perceptions which its presence has 

 called up in his Mind. Thus, when I press my hand against this 

 table, I recognise its unyieldingness through the conjoint medium 

 of my sense of Tonch, my Muscular sense, and my Mental 

 sense of Effort, to which it will be convenient to give the general 

 designation of the Tactile Sense ; and I attribute to that table 

 a hardness which resists the effort I make to press my hand into 

 its substance, whilst I also recognise the fact that the force I 

 have employed is not sufficient to move its mass. But I press 

 my hand against a lump of dough ; and finding that its substance 

 yields under my pressure I call it soft. Or, again, I press my 

 hand against this desk ; and I find that although I do not 

 thereby change its form, I change its place ; and so I get the 

 Tactile idea of Motion. Again, by the impression received 

 through the same Sensorial apparatus, when I lift this book in 

 my hand, I am led to attach to it the motion of weight or pon- 

 derosity ; and by lifting different solids of about the same size, 

 I am enabled, by the different degrees of exertion I find myself 

 obliged to make in order to sustain them, to dtstingnish some of 

 them as light, and others as hrnzy. Through tlie medium of 

 another set of Sense-perceptions which some regard as belonging 

 to a different category, we distinguish between bodies that yirf 

 "hot" and those that y^v/ "cold;" and in tftismauner we 

 arrive at the notion of differences of Temperature, And it is 

 through tire medium of our Tactile Sense, without any aid from 

 Vision, that we first gain the idea of solid form, or the Three 

 Dimensions of Space. 



Again, by the extension of our Tactile experiences, we acquire 

 the notion of liquids, as forms of matter yielding readily to pres- 

 sure, but possessing a sensible weight which may equal that of 

 solids : and of air, whose resisting power is much slighter, and 

 whose weight is so small that it can only be made sensible by 

 artificial means. Thus, then, we arrive at the notions of resist- 

 ance and weight as properties common to all forms of Matter ; 

 and now that we have got rid of that idea of Eight and Heat, 

 Electricity and Magnetism, as "imponderable fluids," which 

 used to vex our souls in our Scientific Childhood, and of which 

 the popular term "Electric Fluid is a "survival," we accept 

 these properties as affording the practical distinction between 

 the "material" and the "immaterial." 



Turning, now, to that other great portal of Sensation, the 

 Sight, through which we receive most ol the messages sent to us 

 from the Universe around, we recognise the same truth. Thus 

 it is agreed alike by Physicists and Physiologists, that .Colour 

 does not exist as such in the object itself; which has merely 

 the power of reflecting or transmitting a certain number of 

 millions of undulations in a second ; and these only produce 

 tliat affection of our conscioiisness which we call Colour, when 

 they fall upon the retina of the living Percipient. And if there 



