158. Where was there ever a body that was indifferent to rest or motion? In all terrestrial bodies we find a tendency to motion, if no other, at least that of gravitation towards the centre of the earth. Celestial bodies, so far as our observation extends, are all in motion; calculation agrees with experience in showing them to be subject to universal attraction: where, then, is the indifference to rest or motion, revealed by experience? We should rather say that experience reveals a general inclination of bodies to be in motion.
159. It would be objected that this inclination does not flow from any activity in the bodies, but that it is a simple effect of a law imposed by the Creator. Let it be so: but at least do not tell us that experience presents bodies as indifferent to motion or rest; explain motion, if you will, without activity, maintain that there is no activity, despite the appearances of experience; but do not tell us that these appearances show the absence of activity.
160. If I place a body on my table, it remains at rest, I find it there the next day, and if I return after many years I still find it there. But this body is not indifferent to motion or rest; here it is at rest, but it is continually exercising its activity, as is evident from its pressure on the table which supports it. This exercise is incessant, it is experienced at every moment; try to raise it and it offers resistance, take away the table and it falls, place your hand under it and it will press upon your hand, and it changes the form of soft bodies on which it rests.
161. To say that the attraction of the centre of the earth acts upon the body, proves nothing against corporeal activity but rather confirms it; for this centre is another body, and thus you take activity from one body to give it to another. Moreover, all observations show that attraction is mutual, and therefore attractive activity is a property of all bodies.
162. The corporeal world, far from appearing to us as an inert mass, presents the appearance of an activity developing its colossal forces. The mass of bodies which move in space is colossal; the orbit which they describe is colossal; their velocity is colossal; the influence, at least apparent, which they exercise upon each other, is colossal; the distance at which they communicate is colossal. Where is the want of activity revealed by experience? Rays of light inundate space, producing in sensitive beings the wonderful phenomena of sight: rays of heat extend in all directions, and motion and life spring up on all sides; where is the want of activity revealed by experience? Do not the vegetation which covers our globe, the phenomena of life which we experience within us, and in the animals around us, require a continual motion of matter, an ebb and flow, so to speak, of action and reaction of bodies on each other, in reality or in appearance? Do not the phenomena of electricity, of magnetism, of galvanism, appear to be principles of great activity, the origin of motion wherever they exist, rather than objects indifferent to motion or rest? The ideas of activity, of force, of impulse, are not alone suggested to us by our internal activity, but also by the experience of the corporeal world, which displays before our eyes, and in obedience to constant laws, a continual variety of magnificent scenes, whose origin seems to indicate a fund of activity surpassing all calculations.
163. With how little reason then do you appeal to experience to combat the existence of causality in bodies, and how much more in accordance with experience are those philosophers who give a true activity to bodies, is apparent from what I have said. In assigning the limits of our intuition in relation to causality and activity in themselves,[94] I said enough to show that I do not judge it possible to demonstrate metaphysically the existence of activity in the corporeal world; yet I cannot but insist that if the constant relation of phenomena in space and time, and the invariable succession of some things after others, prove any thing in favor of causality, we must admit the opinion which holds that there is true activity in bodies; that in a secondary order the reason of the changes of some is contained in others; and that consequently there is in the corporeal world a chain of second causes which reaches back to the first cause, the origin and the reason of all that is.
[CHAPTER XVI.]
INTERNAL CAUSALITY.
164. Consciousness reveals the existence of a faculty within us which produces certain internal phenomena. If we concentrate our attention by means of a free act of our will, we experience the production of images and ideas. The works of the imagination are an irrefutable proof of our internal activity. Sensations furnish the materials; but the fancy builds edifices with them. Who, if not ourselves, gave them their new form? We must confess that if we are absolutely without activity, nature completely deludes us, making us believe that we are active.