INDUCTION AND DEDUCTION. 261 



lars be would construct a whole. The man of science, on the other hand, 

 seeks a reason or principle. From the whole he proceeds by its parts, even 

 to the roots. As the artificer knows nothing of a principle, and a prin- 

 ciple would be of no help to him, it will be understood that the process 

 going on in his mind is no intellectual operation. The intrinsic char- 

 acter of his thought resides in this, that he thinks of sensible phe- 

 nomena. As the understanding examines ideas, measures, as it were, 

 determines and fixes their import, so that they become serviceable for 

 deductive operations, just so does the inductive artificer proceed. He 

 probes the phenomena with all his senses, and while he applies his 

 faculty of perception, with all the tension of his will, to one property 

 of a substance or one pecularity of a phenomenon after another, to 

 the present exclusion of all others, his imaginative power acquires a 

 sharp and definite image of the whole thing, which, like an abstract 

 idea, includes in itself the entire essence of the substance or phenomenon. 

 A blue, black, or yellow color, or the existence of a white precipitate 

 which is soluble or insoluble in a certain acid or alkali, calls up in the 

 mind of the chemist the idea of iron, iodine, kali, magnesia, sulphuric, 

 or muriatic acid, &c., an ideal iron, iodine, &c., altogether different from 

 the conception which men in ordinary life connect with those sub- 

 stances. 



The understanding arrives, through the combination of exact ideas, 

 at conclusions whose truth is only intellectually discernible; the mental 

 combinations of the artificer, on the other hand, are material or capa- 

 ble of being represented to the senses. 



In this peculiar mental process, in which the imaginative jiower 

 plays the principal part, consists essentially the idea which I should be 

 disposed to connect with the word induction, and I do not think that it 

 is in conflict with that of Aristotle. 



It is not easy to convey a clear idea of the nature of the mental ope- 

 rations of the experimental artificer, which, as already said, depend on 

 a combination of -facts or phenomena standing in a similar relation to 

 one another, with the logical ideas which guide the understanding in 

 its conclusions ; from the facts or reactions known to him he determines 

 respecting the existence of a new one before unknown ; his conclusion 

 is again a fact or a reaction ; perhaps it is to the peciTliar fiiculty of the 

 musical composer, who thinks in sounds, that the i^rocess of chemical or 

 physical thinking may be most closely compared. 



In exact research, the 'logic of the explanation of a ])henomenou or 

 demonstration of a j)roblem, rests on facts, which hang together as by 

 the links of a chain, or as by hinges, and whoever will take the trouble 

 to revise a chemical or i^hysical investigation, will at once perceive that 

 a majority of the facts which serve the philosophic inquirer for an 

 explanation or demonstration, do not offer themselves in nature, but 

 that they are first excogitated or devivsed by the inquirer himself; he is 

 necessitated to seek out the facts which are wanting to his mental oper- 



