i The Study of Nature 5 



8. Use of Reason. In spite of such cases of deception, 

 we trust our senses and are rarely deceived by them. 

 Reason, man's supreme gift, examines, weighs, extends, and 

 judges the evidence of the senses. It requires a course of 

 reasoning to let us know that a tall man far off on a straight 

 road is not a dwarf close at hand, or that the Moon rising 

 behind a wood is not a yellow plate hung in the trees. 

 Long practice has made the operation of reason so swift 

 and smooth that we are seldom conscious of an interval 

 between seeing and understanding. Reason makes the 

 senses satisfactory means for acquiring knowledge, although 

 reason alone can give no information about natural things. 

 Just as the senses may be greatly aided by instruments and 

 apparatus, reason may be greatly aided by mathematics. 

 And as accurate measurements, on which the value of all 

 scientific observations depend, can only be made by means 

 of suitable apparatus, sometimes of a very elaborate nature, 

 so accurate reasoning, which is essential in all scientific 

 discussions, can only be fully carried out by mathematical 

 processes which are sometimes difficult and complicated. 



9. Common Sense is the name which practical people 

 give to the best and easiest way of doing their work, and 

 the simplest and completest way of gaining knowledge or 

 explaining any difficulty. Common sense consists of reason- 

 ing on the evidence of the senses, but without keeping 

 account of the process. When this common-sense method 

 is made precise and accurate, it becomes the Scientific 

 Method of gaining knowledge. The two guardians of 

 thought in science are Accuracy and Definiteness. The 

 scientific man deals with phenomena as the banker 

 does with money, counting and recording* everything with 

 scrupulous exactness. The student should remember that 

 for the practical purposes of life the knowledge of what are 

 called scientific facts is unimportant compared with the 

 power of using the scientific method. It is really more 

 scientific to repeat a quotation from a political speech 

 correctly, or to pass on a story undistorted, than it is to 

 know of the rings of Saturn or the striation of diatoms. 



// " 10. Accuracy in observation usually takes the form of 



