THE MECHANISM OF NATURE 295 



before they learn to fly, climb on to the edge of the nest, but they 

 seldom tumble; and they will cling to the finger, when this is 

 inclined, in such a way as to keep their balance. They who 

 believe instinct is inherited knowledge may say the land-crab knows 

 the danger of a fall by instinct; and they may be disposed to 

 think that the intellectual value of our confidence in gravitation 

 is in part innate and independent of experience. 



A single hard tumble may do more to convince a child that 

 unsupported bodies will fall than long impersonal experience; and 

 the intensity of any conviction which is consistent with our natu- 

 ral adjustments cannot be measured by the amount of experience, 

 although this is the only measure of its value as knowledge, for 

 we have no other way to learn when and how far an adjustment 

 is judicious, and when it is not, than through experience of the 

 order of nature. The question we now seek to answer is not 

 how strong our confidence in gravitation is, but what it is worth, 

 and we find that its value as knowledge may be measured, quan- 

 titatively as well as qualitatively, by human experience, and that 

 it has no inherent or a priori intellectual value; although the 

 practical value, in preserving life, of the responses of living things 

 to the stimulus of gravitation is often independent of experience; 

 and although we may, in these cases, be quite unable to tell 

 whether these responses are accompanied by mind or not. 



Ignorance is not knowledge, as we use words ; and one school 

 of "philosophers" seems to me to have brought needless confu- 

 sion into the discussion of the nature and sources of human 

 knowledge by failure to distinguish the practical value to living 

 things of response to the order of nature from the logical value 

 of our own conscious intelligent confidence in the stability of this 

 order; for whether these things are fundamentally different or 

 not, they are practically different for us. 



In another school of "philosophers," who teach that our minds 

 would lose their value unless we have a monopoly of reason, 

 equal confusion seems to me to follow failure to perceive that 

 every responsive action in nature may, for all we know to the 

 contrary, be accompanied by some small part of that which we 

 call mind. 



If our scientific creed is a modest confession that while we 



