60 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH. 



scarcely an appreciable amount of either time or atten- 

 tion. That of a compound ^idea is less easily or quickly 

 formed. The mental realisation of a comparison occupies 

 more of our time and attention. And that of an inference, 

 an abstruse idea, or of a composite panoramic one, requires 

 a still greater and more prolonged mental effort, and cannot 

 under any circumstances be as distinctly conceived as a 

 simpler or less abstruse one, and we usually clearly per- 

 ceive only its salient points. The farther an idea is 

 removed in any respect from our actual experience, the 

 more difficult is it to realise it ; we can more accurately 

 imagine one than one thousand, or than a thousandth part 

 of one ; a second than an hour, or a thousandth part of a 

 second ; an inch than a mile, or a thousandth part of an 

 inch, and so on. 



The acquisition of ideas depends largely upon obser- 

 vation; and observation is usually a state of conscious 

 perception. Observation is either automatic or voluntary. 

 Automatic observation is that which occurs independently 

 of our will, and is the spontaneous result of the various and 

 ever-changing causes which excite our perception. Volun- 

 tary observation or attention is a conscious mental effort 

 to perceive an object or idea already present ; it is that in 

 which the will also operates, to intensify the action of the 

 nervous power flowing to the organs of sense and percep- 

 tion, by means of which we observe. 



Much of the success in original scientific research 

 depends upon the will. Conscious mental effort is necessary 

 to a greater extent, perhaps, in this occupation than in 

 any other, because the subjects are more novel and abstruse. 

 The more difficult the mental labour, the greater must be 

 the determination and energy of thought required to effect 

 it. Without the powerful exertion of volition, many of 



