VAEIOUS MODES OF DISCOVERY. 



largely of the physical labour of travelling ; in the various 

 sciences of mechanics, heat, light, electricity, magnetism, 

 chemistry, and physiology, it generally consists of obser- 

 vation, study, and experiment in varied proportions ; in 

 the sciences of astronomy, meteorology, and geology it 

 lies chiefly in observation and study, with but compara- 

 tively little experiment. In all these cases the scientific 

 investigator continually forgets the things which are be- 

 hind, and reaches forth unto those which are before. 



Discovery consists in passing from the known to the 

 unknown. We pass from the known to the unknown in 

 the following cases : 1. When we perceive a new impres- 

 sion ; the man who first saw a bit of native gold, or felt 

 an electric spark, made a discovery. 2. When we observe 

 a new fact ; as Galileo, when he first observed the moons 

 of Jupiter. 3. When we compare two ideas, and observe 

 a new similarity or difference ; as he who first noticed 

 that steel as well as loadstone was capable of retaining 

 magnetism. 4. When we compare two propositions, and, 

 perceiving a similarity or difference, infer a new truth. 

 5. When we divide or analyse a compound idea, and per- 

 ceive a new and more elementary one. 6. When we com- 

 bine two or more ideas together by an act of imagination, 

 and perceive a new combination. And 7. When we per- 

 mutate or alter the order of a series of ideas, and perceive 

 a new harmonious order. 



Both science and art are involved in discovery : science 

 in the principles which govern it, and art in its practice. 

 That scientific discovery is really an art and not wholly a 

 gift of nature to men of genius, is proved by the fact that 

 it may be largely reduced to a system of practical rules 

 and methods, and also because skill in it is increased by 

 education and by practice of those rules. 



It is the most highly intellectual of all the arts, 



