SECTION 22 OBSERVATION. 275 



braces the most diverse psychological elements. In some cases 

 people believe themselves to be descendants of the animal 

 whose protection they enjoy. In other cases an animal or some 

 other object may have appeared to an ancestor of the social 

 group, and may have promised to become his protector, and 

 the friendship between the animal and the ancestor was then 

 transmitted to his descendants. In still other cases a certain 

 social group in a tribe may have the power of securing by 

 magical means and with great ease a certain kind of animal 

 or of increasing its numbers, and the supernatural relation may 

 be established in this way." (The Mind of Primitive Man, 1911, 

 pp. 190-191.) Lastly, it is very general, for psychological 

 reasons, to favour a tripartite classification of facts, when the 

 number should be far higher as a rule. At all times, in short, 

 men have regarded the complex as simple and that which is 

 divisible as indivisible, and have been seriously deceived on 

 this account. 



In the fiftieth aphorism of the first book of his Novum 

 Organum Bacon places his finger on the weakest spot in all 

 non-scientific speculation. He acutely remarks that "speculation 

 commonly ceases where sight ceases; inasmuch that of things 

 invisible there is little or no observation". Almost the entire 

 history of science is an exemplification of this aphorism, for 

 that which strikes the unassisted senses is most generally of 

 small consequence in leading to scientific advance. We have 

 only to think of chemical elements and their modes of com- 

 bining, of the constitution of the air, of heat, light, and electri- 

 city, of the formation of the strata of the earth, of protoplasm, 

 and of the cell structure of all that lives, of the assimilation 

 of food by plants and animals, of the specio-historical character 

 of man's mental outfit, of the bacterial origin of many diseases, 

 to appreciate the fact that the subtlety of nature escapes ordinary 

 perception, and that non-scientific or common speculation, must 

 needs be barren and erroneous since it is necessarily based 

 on unaided perception which brings together what is separate 

 and separates what is united. 1 Darwin rightly watched for ex- 

 ceptions, because these alone, generally speaking, point to 

 primary factors, whereas what is present to vision as such is 



1 The recent investigations relating to radio-activity illustrate the above con- 

 tention: "The quantity of radium present in pitch-blende is extremely small, 

 many tons of the material yielding, after long and tedious work, only a small 

 fraction of a gramme of an impure salt of radium." (Whetham, The Recent 

 Development of Physical Science, 1904, p. 202.) Likewise, " Sir William Roberts- 

 Austen has shown that gold, if placed in intimate contact with lead, will 

 diffuse at ordinary temperatures to such an extent that, after the lapse of 

 some years, it can be detected in the lead by chemical analysis at distances 

 of a millimetre or more from the surface of contact."^ (Ibid., p. 247.) Also, 

 many metals occlude or absorb considerable quantities of hydrogen and 

 certain quantities of oxygen. (A. H. Hiorns, Principles of Metallurgy, 1914, 

 pp. 10-11.)- 



