748 POPULAR SCIENCE MONTHLY. 



tastes, and touches flow round him in limitless variety. Of 

 many, perhaps of most, he is never conscious ; to only a few does 

 he respond. 



Objection may be made to the analogy, but on examination I 

 am sure it will be found to be sufficiently close for our own pur- 

 pose. To the mind, sounds, tastes, colors, odors, and sights are 

 what foods are to the sponge they are stimuli. Specialists on 

 the eye tell us that the range of light vibrations to which the 

 human eye responds is but a little break in a great series, like a 

 short stretch cut out of the middle of an inclined plane. So, too, 

 with our ears. They can intercept only a few of the possible 

 sound vibrations that make up the world of noises. As the 

 sponge, then, comes in contact with but the merest vialful of the 

 great ocean, the human organism also makes contact with mere 

 fragments of the world's infinity of stimuli. 



There is a second respect in which the analogy holds good. 

 Just as, out of the limited flow of food-laden sea water that passes 

 its doors, the sponge chooses what it needs, what it can assimilate, 

 so the human organism, out of the limited variety of stimuli to 

 which it is competent to reach, chooses such to respond to as are 

 important. 



Now, what has this to do with belief ? Simply this, that belief, 

 whatever else it may be, is a human function, and in so far as it 

 is vital and important it must be subject to the fundamental 

 laws of the organism. We can neither believe nor disbelieve 

 what we never come in contact with, and the stress of life causes 

 us to believe only what is important to us, as the sponge absorbs 

 only what will nourish it. I do not say we are incapable of be- 

 lieving a thing that is useless for us. It is possible for an organ- 

 ism to take and to treat as food that which is valueless. But in 

 the main, life means taking what is good, and taking what is not 

 good means death. This is as true of the mental life as it is of 

 the physical life, and for the most part the process of choice is 

 instinctive and unconscious. When the thermometer falls we 

 have sensations of discomfort we may respond by taking off our 

 clothing. It is conceivable that we should believe it is getting 

 hot. But we do actually respond by putting on our overcoats, 

 which is good evidence that we believe it is cold. 



This, I take it, is what Prof. Bain meant when he said, " In its 

 essential character belief is a phase of our active nature," and I 

 do not think it conflicts in any way with Hume's account of belief 

 as a "more vivid, lively, forcible, firm, steady conception than 

 the imagination is able to attain." In fact, both of these accounts 

 seem to me very true. What I mean by believing my friend's 

 word is not that I have a clear perception that his words repre- 

 sent definite things, but that I conceive the main thing he de- 



