340 PSYCHOLOGY. 



have a student's lamp of which the flame vibrates most un- 

 pleasantly unless the collar Avhich bears the chimney be 

 raised about a sixteenth of an inch. I learned the remedy 

 after much torment by accident, and now always keep the 

 collar up with a small wedge. But my procedure is a mere 

 association of two totals, diseased object and remedy*. One 

 learned in pneumatics could have named the cause of the 

 disease, and thence inferred the remedy immediately. By 

 many measurements of triangles one might find their area 

 always equal to their height multiplied by half their base, 

 and one might formulate an empirical law to that effect. 

 But a reasoner saves himself all this trouble by seeing that 

 it is the essence [pro hoc vice) of a triangle to be the half of 

 a parallelogram whose area is the height into the entire 

 base. To see this he must invent additional lines ; and the 

 geometer must often draw such to get at the essential prop- 

 erty he may require in a figure. The essence consists in 

 some relation of the Jigirre to the ne70 lines, a relation not ob- 

 vious at all until they are put in. The geometer's sagacity 

 lies in the invention of the new lines. 



THUS, THERE ARE TWO GREAT POINTS IN" REASONING: 



First, an extracted character is tal^en as equivalent to the 

 entire datum from luhich it comes ; and., 



Second, the character thus taken suggests a certain conse- 

 quence more obviously than it ivas suggested hy the total datum. 

 as it originally came. Take them again, successively. 



1. Suppose I say, when offered a piece of cloth, " I Avon't 

 buy that; it looks as if it would fade," meaning merely 

 that something about it suggests the idea of fading to my 

 mind, — my judgment, though possibly correct, is not rea- 

 soned, but purel}^ empirical ; but, if I can say that into the 

 color there enters a certain dj^e which I know to be chemi- 

 cally unstable, and that therefore the color will fade, my judg- 

 ment is reasoned. The notion of the dye which is one of the 

 parts of the cloth, is the connecting link between the latter 

 and the notion of fading. So, again, an uneducated man 

 will expect from past experience to see a piece of ice melt 

 if placed near the fire, and the tip of his finger look coarse 



