ULTIMATE SCIENTIFIC IDEAS. 59 



be equidistant from boundaries that do not exist. Thus 

 while we are obliged to think that there is an absolute mo- 

 tion, we find absolute motion incomprehensible. 



Another insuperable difficulty presents itself when 

 we contemplate the transfer of Motion. Habit blinds 

 us to the marvelousness of this phenomenon. Familiar 

 with the fact from childhood, we see nothing remark- 

 able in the ability of a moving thing to generate 

 movement in a thing that is stationary. It is, how- 

 ever, impossible to understand it. In what respect 

 does a body after impact differ from itself before impact? 

 What is this added to it which does not sensibly affect any 

 of its properties and yet enables it to traverse space? 

 Here is an object at rest and here is the same object moving. 

 In the one state it has no tendency to change its place ; but 

 in the other it is obliged at each instant to assume a new 

 position. What is it which will for ever go on producing 

 this effect without being exhausted? and how does it dwell 

 in the object? The motion you say has been communicated. 

 But how? What has been communicated? The striking 

 body has not transferred a thing to the body struck; and it 

 is equally out of the question to say that it has transferred 

 an attribute. What then has it transferred? 



Once more there is the old puzzle concerning the con- 

 nexion between Motion and Rest. We daily witness the 

 gradual retardation and final stoppage of things projected 

 from the hand or otherwise impelled ; and we equally often 

 witness the change from Rest to Motion produced by the 

 application of force. But truly to represent these transi- 

 tions in thought, we find impossible. For a breach of the 

 law of continuity seems necessarily involved; and yet no 

 breach of it is conceivable. A body travelling at a given 

 velocity cannot be brought to a state of rest, or no velocity, 

 without passing through all intermediate velocities. At 

 first sight nothing seems easier than to imagine it doing this. 

 It is quite possible to think of its motion as diminishing in- 



