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, and so on indefinitely. It is true that we say there must be something else, viz., the actual passing across the interval which separates those positions. But such a conception of Change is quite false. All true change or movement is indivisible. We, by constructing fictitious states and trying to compose movement out of them, endeavour to make a process coincide with a thing--a movement with an immobility. This is the way to arrive at dilemmas, antinomies, and blind-alleys of thought. The puzzles of Zeno about "Achilles and the Tortoise" and "The Moving Arrow" are classical examples of the error involved in treating movement as divisible.[Footnote: Bergson in Matter and Memory examines Zeno's four puzzles: "The Dichotomy," "Achilles and the Tortoise," "The Arrow" and "The Stadium."] If movement is not everything, it is nothing, and if we postulate, to begin with, that the motionless is real, then we shall be incapable of grasping reality. The philosophies of Plato, of Aristotle, and of Plotinus were developed from the thesis that there is more in the immutable than in the moving, and that it is by way of diminution that we pass from the stable to the unstable.