M A M M A L I A. 



product must be a constant quantity, the two elements 

 power and time are in reciprocal proportion, that is, the 

 one of them increases as the other diminishes, at such 

 a rate as that, the product shall remain the same. 

 Thus, for instance, if the whole force is expressible 

 by the number 16, and the power and time are sup- 

 posed equal, each will be expressed by the number 4 ; 

 if one of them is multiplied by any number, the other 

 must be divided by the same, as, for instance, if 

 the power, 4, is doubled so as to become 8, the other, 

 the time, must be halved so as to become 2 ; and so 

 on in all other proportions, their proportion to each 

 other being- the greater equal to the less multiplied 

 by the square of the number, which multiplied the 

 one and divided the other in the case of their nume- 

 rical equality. In consequence of this law of variation, 

 cither the power or the time requisite for the per- 

 formance of any given effect may be imagined to 

 become as small as we please, provided the other 

 increases as much by multiplication as this one dimi- 

 nishes by division. Neither of them can, however, in 

 any imaginable case become nothing, or arithmetically 

 speaking equal to 0, because if one of two factors is 

 the product is 0, whether the other factor be great 

 or small. 



The necessary inference from this is, that every 

 action of a material creature, whether it consist in 

 observation by the senses, or in the mechanical exer- 

 cise of the muscles, must require both exertion and 

 time for its performance. We do not require to state 

 the numerical relation of these to each other, because 

 that varies in every particular case ; but we must 

 bear in mind that this is the general principle, and 

 when we apply it to animals we must distinctly un- 

 derstand that both elements enter into every possible 

 animal effort, whether quick or slow, feeble or ener- 

 getic, and that this holds in the case of all animals, 

 in consequence of the bodies of animals being material, 

 and as such necessarily subject to the law of gravita- 

 tion, to the exact amount of the quantity of matter 

 concerned in the parts by and upon which the animal 

 action is performed. 



Mind, from the very definition of it, is completely 

 absolved from this law of gravitation ; and conse- 

 quently the action of mind, whatever it may be, re- 

 quires neither effort nor time for its performance. It 

 does not fatigue, and it occupies no measurable dura- 

 tion. In consequence of this, multiplicity of thought 

 (for thought is the general name in common language 

 for the operation of mind) cannot by possibility 

 diminish the capacity of thinking, on any one par- 

 ticular subject, in the same manner as multiplicity of 

 observation by the senses, or of muscular effort in 

 action, diminishes the bodily power in the individual 

 instance. On the contrary, the greater the abundance 

 of the materials or subjects of thought, thinking be- 

 comes the more ready. The proper function of the 

 mind, as we feel it in ourselves and judge of it by the 

 conduct of others, is comparison, and an inference 

 drawn from that comparison. The correctness of 

 the comparison, and the truth and applicability of 

 the inference, are the valuable parts of thought ; and 

 it is impossible for us to obtain these in such a way 

 as that the comparison may be correct, and the infer- 

 ence useful, unless the grounds of our judgment are 

 complete. Nature, which is the source of all our 

 materials of thinking, as concerns our drawing of in- 

 ferences, and acting- upon them through the instru- 

 mentality of the body, is one system, all the parts of 



NAT. 'HIST. Vor.'. III. 



which have an intimate relation to each other ; and 

 consequently the foundations of our comparison must 

 fall short of accuracy, in every case, in proportion as 

 we are ignorant of the nature and relations of the 

 whole. 



It follows from this, that, as mind is the opposite 

 of matter in definition, the perfection of its exercise 

 must be the opposite of that of the exercise of matter ; 

 and that combination of thought is as essential to the 

 useful exercise of the mind, as the division of labour 

 is to the useful exercise of the body. 



This distinction between the most profitable uses 

 of the two parts of the compound nature of man may 

 be said to be the very key of knowledge, and from 

 want of it, or ignorance of the use of it, countless 

 thousands of men in all ages have drudged in thought 

 during the whole period of their lives, in a manner 

 scarcely more profitable than if they had never thought 

 at all. 



It is to be regretted that there is a wonderful 

 proneness to this confounding of mind and matter, 

 and making the latter the model or example of the 

 former. We see the advantages of the division of 

 labour by the body, for they are at once palpable to 

 the senses, in the improved products of bodily labour, 

 and the successful conducting of bodily action ; and 

 as the effect of a particular mode of conducting 

 thought is not an object of the senses in any meaning 

 of the word, but a result which can be arrived at onlv 

 by the mind itself, it is not suggested to the mind 

 until the mind has acquired that general knowledge 

 of relations in which it consists. This is the reason 

 why technical men, in matters of thought, are always 

 narrow-minded, and incapable of turning their own 

 technical knowledge to that use to which it might be 

 turned. To use a homely simile, they are in posses- 

 sion of a single bone of the skeleton, loosened from 

 its connexion, and thus are unable to come to any 

 conclusions as to the structure and the functions of 

 that species of animal to which the bone belongs. 



To some this may seem irrelevant to the study of 

 the mammalia, but the truth is exactly the reverse ; 

 and we have a remarkable instance of it in the case 

 of the late Baron Cuvier. Before the time of that 

 most illustrious of generalising naturalists, there were 

 conjectures about the extinct mammalia, of which 

 single bones are found buried in the soil ; and there 

 were classifications of mammalia, better in some in- 

 stances and worse in others, but all imperfect. Cuvier 

 did not sit down to dote and dream over the fossil 

 bone, and eke out the scanty information which it 

 afforded by foundationless conjectures. He went 

 straight to the living mammalia, dissected them bone 

 by bone, in an immense number of different species ; 

 and in every case he took heed of the leading func- 

 tions which were inseparably connected with every 

 varied form of the skeleton. By patient, skilful, and 

 most truly philosophical labour in this way, he learned 

 to make a single bone an index to the general cha- 

 racter of an animal ; and by this means he caused 

 the extinct races to stand up before the intelligent 

 mind, clothed with sinews and with flesh, and per- 

 forming their functions as palpably and as intelligibly 

 to the understanding as if they were now tenanting 

 the earth in the living state. 



The result of this was the classification of animals 

 in the " Regne Animal," of which we shall give a 

 brief outline in the sequel ; and which, at least in 

 those parts which were moulded by his master hand, 



