32 The Relativity of Knoivledge. 



how he can have motion unless there is something, not 

 itself motion, that can be moved. If all human experi- 

 ences are due to motions, what is the unknown something 

 that makes motion possible ? On a ship coming from Liv- 

 erpool to New York, if you walk from stem to stern at the 

 rate of three miles an hour, you may be very certain that 

 you are moving, and those of your fellow-passengers who 

 see you are equally positive. If the boat is going with 

 just the same speed in the opposite direction, it becomes 

 evident that you were all mistaken. As you walked east- 

 ward you no doubt were confident of the direction of your 

 motion ; yet if the boat was going thirty miles per hour in 

 the opposite direction, it is clear that instead of going 

 three miles eastward, as you at first believed, you were 

 really going twenty-seven miles an hour westward. But 

 ^ven this correction can be challenged. The earth carries 

 boat, ocean and passengers at a rate of about 1,000 miles 

 per hour eastward, so that it seems you are going East 

 after all at the rate of about 973 miles per hovu-. Again, 

 this can be challenged ; for the orbital motion changes all 

 our previous computations. Once more, this last can be 

 challenged, for the movement of the solar system among 

 the fixed stars must be considered. Motion cancels motion 

 as we go along in our discoveries, until we finally see that, 

 for aught we know to the contrary, every motion ever made, 

 considered absolutely, may be a mere illusion of sense, due 

 to position, as in the cases we have noted. 



Could we trace our way through the depths of infinity, 

 we have no reason for assuming that the cancellations, 

 both in direction and time, are not endless. Analogy would 

 say they are. Who then can ever know whether or not 

 there ever was any such thing as an absolute change of 

 place at all ? Of relative change we have an abundance of 

 evidence ; of absolute change, none. As science on tlie 

 one hand resolves everything into motion, and on the otlun* 

 hand proves that we have no evidence of the actiuil exist- 

 ence of motion, it very plainly cancels its own testimony 

 and leaves us without a guide. 



In considering the physiology of sensation, this cancel- 

 lation becomes still more complete. The thought of a 

 moving body is but a mode of consciousness. The whirl 

 of a wheel gives us no evidence that it, too, is a mode of 

 consciousness. We can truly picture with some approach 



