THE SIX ENNEADS [217]
as a certain limitation; this, though, will not be the case where the element introduced is of a kind to overleap the bridge. But this is saying that the sympathetic quality of the universe depends upon its being one living thing, and that our amenability to experience depends upon our belonging integrally to that unity; would it not follow that continuity is a condition of any perception of a remote object? The explanation is that continuity and its concomitant, the bridging substance, come into play because a living being must be a continuous thing, but that, none the less, the receiving of impression is not an essentially necessary result of continuity; if it were, everything would receive such impression from everything else, and if thing is affected by thing in various separate orders, there can be no further question of any universal need of intervening substance. Why it should be especially requisite in the act of seeing would have to be explained: in general, an object passing through the air does not affect it beyond dividing it; when a stone falls, the air simply yields; nor is it reasonable to explain the natural direction of movement by resistance; to do so would bring us to the absurdity that resistance accounts for the upward movement of fire, which on the contrary, overcomes the resistance of the air by its own essentially quick energy. If we are told that the resistance is brought more swiftly into play by the very swiftness of the ascending body, that would be a mere accidental circumstance, not a cause of the upward motion: in trees the upthrust from the root depends on no such external propulsion; we, too, in our movements cleave the air and are in no wise forwarded by its resistance; it simply flows in from behind to fill the void we make. If the severance of the air by such bodies leaves it unaffected, why must there be any severance before the images of sight can reach us? And, further, once we reject the theory that these images reach us by way of some outstreaming from the objects seen, there is no reason to think of the air being affected and passing on to us, in a progression of impression, what has been impressed upon itself. If our perception is to depend upon previous impressions made upon the air, then we have no direct knowledge of the object of vision, but know it only as through an intermediary, in the same way as we are aware of warmth where it is not the distant fire itself that warms us, but the warmed intervening air. That is a matter of contact; but sight is not produced by contact: the application of an object to the eye would not produce sight; what is required is the illumination of the intervening medium; for the air in itself is a dark substance: If it were not for this dark substance there would probably be no reason for the existence of light: the dark intervening matter is a barrier, and vision requires that it be overcome by light. Perhaps also the reason why an object brought close to the eye cannot be seen is that it confronts us with a double obscuration, its own and that of the air. 3. For the most convincing proof that vision does not depend upon the transmission of impressions of any kind made upon the air, we have only to consider that in the darkness of night we can see a fire and the stars and their very shapes. No one will pretend that these forms are reproduced upon the darkness and come to us in linked progression; if the fire thus rayed out its own form, there would be an end to the darkness. In the blackest night, when the very stars are hidden and show no gleam of their light, we can see the fire of the beacon-stations and of maritime signal-towers. Now if, in defiance of all that the senses tell us, we are to believe that in these examples the fire [as light] traverses the air, then, in so far as anything is visible, it must be that dimmed reproduction in the air, not the fire itself. But if an object can be seen on the other side of some intervening darkness, much more would it be visible with nothing intervening. We may