58 ULTIMATE SCIENTIFIC IDEAS. 



in its orbit, we have to join that of the whole Solar system 

 towards the constellation Hercules; and when we do this, 

 we perceive that he is moving neither East nor West, but in 

 a line inclined to the plane of the Ecliptic, and at a velocity 

 greater or less (according to the time of the year) than that 

 above named. To which let us add, that were the dynamic 

 arrangements of our sidereal system fully known to us, we 

 should probably discover the direction and rate of his actual 

 movement to differ considerably even from these. How 



illusive are our ideas of Motion, is thus made sufficiently 

 manifest. That which seems moving proves to be station- 

 ary; that which seems stationary proves to be moving; 

 while that which we conclude to be going rapidly in one 

 direction, turns out to be going much more rapidly in the 

 opposite direction. And so we are taught that what we are 

 conscious of is not the real motion of any object, either in its 

 rate or direction; but merely its motion as measured from 

 an assigned position — either the position we ourselves oc- 

 cupy or some other. Yet in this very process of concluding 

 that the motions we perceive are not the real motions, we 

 tacitly asuine that there are real motions. In revising our 

 successive judgments concerning a body's course or velo- 

 city, we take for granted that there is an actual course and 

 an actual velocity — we take for granted that there are fixed 

 points in space with respect to which all motions are abso- 

 lute ; and we find it impossible to rid ourselves of this idea. 

 Nevertheless, absolute motion cannot even be imagined, 

 much less known. Motion as taking place apart from those 

 limitations of space which we habitually associate with it, is 

 totally unthinkable. Eor motion is change of place ; but in 

 unlimited space, change of place is inconceivable, because 

 place itself is inconceivable. Place can be conceived only by 

 reference to other places; and in the absence of objects dis- 

 persed through space, a place could be conceived only in 

 relation to the limits of space; whence it follows that in 

 unlimited space, place cannot be conceived — all places must 



