ILLUSTRATIONS OF THE LOGIC OF SCIENCE. 289 



maturity with regard to clearness comes rather late, an unfortunate 

 arrangement of Nature, inasmuch as clearness is of less use to a man 

 settled in life, whose errors have in great measure had their effect, 

 than it would be to one whose path lies before him. It is terrible to 

 see how a single unclear idea, a single formula without meaning, lurk- 

 ing in a young man's head, will sometimes act like an obstruction of 

 inert matter in an artery, hindering the nutrition of the brain, and 

 condemning its victim to pine away in the fullness of his intellectual 

 vigor and in the midst of intellectual plenty. Many a man has cher- 

 ished for years as his hobby some vague shadow of an idea, too mean- 

 ingless to be positively false ; he has, nevertheless, passionately loved 

 it, has made it his companion by day and by night, and has given to 

 it his strength and his life, leaving all other occupations for its sake, 

 and in short has lived with it and for it, until it has become, as it were, 

 flesh of his flesh and bone of his bone ; and then he has waked up 

 some bright morning to find it gone, clean vanished away like the 

 beautiful Melusina of the fable, and the essence of his life gone with 

 it. I have myself known such a man ; and who can tell how many 

 histories of circle-squarers, metaphysicians, astrologers, and what not, 

 may not be told in the old German story ? 



II. 



The principles set forth in the first of these papers lead, at once, 

 to a method of reaching a clearness of thought of a far higher grade 

 than the "distinctness" of the logicians. "VVe have there found that 

 the action of thought is excited by the irritation of doubt, and ceases 

 when belief is attained ; so that the production of belief is the sole 

 function of thought. All these words, however, are too strong for 

 my purpose. It is as if I had described the phenomena as they ap- 

 pear under a mental microscope. Doubt and Belief, as the words are 

 commonly employed, relate to religious or other grave discussions. 

 But here I use them to designate the starting of any question, no mat- 

 ter how small or how great, and the resolution of it. If, for instance, 

 in a horse-car, I pull out my purse and find a five-cent nickel and five 

 coppers, I decide, while my hand is going to the purse, in which way I 

 will pay my fare. To call such a question Doubt, and my decision 

 Belief, is certainly to use words very disproportionate to the occasion. 

 To speak of such a doubt as causing an irritation which needs to be 

 appeased, suggests a temper which is uncomfortable to the verge 

 of insanity. Yet, looking at the matter minutely, it must be admit- 

 ted that, if there is the least hesitation as to whether I shall pay the 

 five coppers or the nickel (as there will be sure to be, unless I act 

 from some previously contracted habit in the matter), though irrita- 

 tion is too strong a word, yet I am excited to such small mental activ- 

 ity as may be necessary to deciding how I shall act. Most frequently 



VOL. XII. 19 



