the same movement.  There would then be two movements, with an interval of rest.  Neither from within, by the muscular sense, nor from without, by sight, should we have the same perception.  If we leave our movement from A to B such as it is, we feel it undivided, and we must declare it indivisible.  It is true that when I look at my hand, going from A to B, traversing the interval ab, I say to myself ’the interval ab can be divided into as many parts as I wish, therefore the movement from A to B can be divided into as many parts as I like, since this movement covers this interval,’ or, again, ’At each moment of its passing, the moving object passes over a certain point, therefore we can distinguish in the movement as many stopping-places as we wish—­therefore the movement is infinitely divisible.’  But let us reflect on this for a minute.  How can the movement possibly coincide with the space which it traverses?  How can the moving coincide with the motionless?  How can the object which moves be said to ‘be’ at any point in its path?  It passes over, or, in other words, it could ‘be’ there.  It would ‘be’ there if it stopped there, but, if it stopped there, it is no longer the same movement with which we are dealing.  It is always at one bound that a trajectory is traversed when, on its course, there is no stoppage.  The bound may last a few seconds, or it may last for weeks, months, or years, but it is unique and cannot be decomposed.  Only, when once the passage has been made, as the path is in space, and space is infinitely divisible, we picture to ourselves the movement itself as infinitely divisible.  We like to imagine it thus, because, in a movement it is not the change of position which interests us, it is the positions themselves which the moving object has left, which it will take up, which it might assume if it were to stop in its course.  We have need of immobility, and the more we succeed in presenting to ourselves the movement as coinciding with the space which it traverses, the better we think we understand it.  Really, there is no true immobility, if we imply by that, an absence of movement."[Footnote:  Translated from La Perception du Changement, pp. 19-20.] This immobility of which we have need for the purposes of action and of practical life, we erect into an absolute reality.  It is of course convenient to our sense of sight to lay hold of objects in this way; as pioneer of the sense of touch, it prepares our action on the external world.  But, although for all practical purposes we require the notion of immobility as part of our mental equipment, it does not at all help us to grasp reality.  Then we habitually regard movement as something superadded to the motionless.  This is quite legitimate in the world of affairs; but when we bring this habit into the world of speculation, we misconceive reality, we create lightheartedly insoluble problems, and close our eyes to what is most alive in the real world.  For us movement is one position, then another position,