374 NATURE AND MAN. 



first framed the conception and his vast mathematical ability, 

 which enabled him to give it definite shape that the moon is 

 constantly &quot; falling &quot; towards the earth at a rate exactly conform 

 able to that &quot; law &quot; of terrestrial gravitation, with which the name 

 and fame of Galileo will ever be associated. 



My own first ideas of the Newtonian Philosophy, if I rightly 

 remember, were drawn from the answer given in that best child s 

 book of my generation &quot;Evenings at Home&quot; to the question 

 &quot;Why does an apple fall?&quot; Whether the apple of Newton is to 

 be relegated, like that of Tell, to the limbo of &quot; myths,&quot; is a question 

 I shall not stop to discuss. It is enough that the story serves to 

 illustrate the &quot; idea.&quot; Probably if the question were put to a 

 hundred &quot;educated&quot; people, ninty-nine of them would give one of 

 these two answers, &quot;Because of the earth s attraction,&quot; or, &quot; Because 

 of the law of gravitation.&quot; But, as I have shown, to speak of the 

 attraction of the earth, is merely to express, in different words, the 

 fact that it &quot;draws&quot; the apple downwards; and if we go further 

 and say that the earth draws downwards not only apples, but 

 stones, water, and air in fact, all material bodies whatever we 

 only express a general uniformity, of which we know nothing more 

 than that it is. Clearly it is no real &quot;explanation&quot; of the fall of 

 any one apple, to say that all apples or all material bodies fall 

 when unsupported. So the &quot; law &quot; of gravitation is merely an 

 expression of that general uniformity, framed with a scientific 

 exactness which enables us to say &quot; with certainty &quot; (in common 

 parlance) what will be the time occupied in the fall of a heavy body 

 through any given number of feet. But that &quot;certainty&quot; depends 

 not upon any &quot; governing &quot; action of the &quot; law &quot; itself, for into the 

 purely scientific conception of law the idea of a governing power 

 does not enter ; but solely upon our rational expectation that 

 what has been found conformable to a vast experience in the past, 

 under every variety of conditions, will in like manner prove con 

 formable to it in the future. 



Before, however, we follow the development of Galileo s 

 doctrine of terrestrial gravitation into the Newtonian doctrine of 

 universal gravitation, we must deal with another of the &quot;laws&quot; 

 imposed on Nature by the ancient philosophy. It was held that 

 as a circle is the most &quot;perfect &quot; figure, and as the motions of the 



