(7) Consider the act of ocular vision:

There are two elements here; there is the form perceptible to the sense and there is the medium by which the eye sees that form. This medium is itself perceptible to the eye, distinct from the form to be seen, but the cause of the seeing; it is perceived at the one stroke in that form and on it and, hence, is not distinguished from it, the eye being held entirely by the illuminated object. When on the contrary this medium presents itself alone it is seen directly- though even then actual sight demands some solid base; there must be something besides the medium which, unless embracing some object, eludes perception; thus the light inherent to the sun would not be perceived but for the solidity of the mass. If it is objected that the sun is light entire, this would only be a proof of our assertion: no other visible form will contain light which must, then, have no other property than that of visibility, and in fact all other visible objects are something more than light alone.

So it is with the act of vision in the Intellectual Principle.

This vision sees, by another light, the objects illuminated by the First Principle: setting itself among them, it sees veritably; declining towards the lower Nature, that upon which the light from above rests, it has less of that vision. Passing over the visible and looking to the medium by which it sees, then it holds the Light and the source of Light.

But since the Intellectual-Principle is not to see this light as something external we return to our analogy; the eye is not wholly dependent upon an outside and alien light; there is an earlier light within itself, a more brilliant, which it sees sometimes in a momentary flash. At night in the darkness a gleam leaps from within the eye: or again we make no effort to see anything; the eyelids close; yet a light flashes before us; or we rub the eye and it sees the light it contains. This is sight without the act, but it is the truest seeing, for it sees light whereas its other objects were the lit not the light.

It is certainly thus that the Intellectual-Principle, hiding itself from all the outer, withdrawing to the inmost, seeing nothing, must have its vision- not of some other light in some other thing but of the light within itself, unmingled, pure, suddenly gleaming before it;

(7) We can scarcely do better, in fine, than follow Plato.

Thus:

In the universe as a whole there must necessarily be such a degree of solidity, that is to say, of resistance, as will ensure that the earth, set in the centre, be a sure footing and support to the living beings moving over it, and inevitably communicate something of its own density to them: the earth will possess coherence by its own unaided quality, but visibility by the presence of fire: it will contain water against the dryness which would prevent the cohesion of its particles; it will hold air to lighten its bulky matters; it will be in contact with the celestial fire- not as being a member of the sidereal system but by the simple fact that the fire there and our earth both belong to the ordered universe so that something of the earth is taken up by the fire as something of the fire by the earth and something of everything by everything else.

This borrowing, however, does not mean that the one thing taking-up from the other enters into a composition, becoming an element in a total of both: it is simply a consequence of the kosmic fellowship; the participant retains its own being and takes over not the thing itself but some property of the thing, not air but air's yielding softness, not fire but fire's incandescence: mixing is another process, a complete surrender with a resultant compound not, as in this case, earth- remaining earth, the solidity and density we know- with something of fire's qualities superadded.

We have authority for this where we read:

"At the second circuit from the earth, God kindled a light": he is speaking of the sun which, elsewhere, he calls the all-glowing and, again, the all-gleaming: thus he prevents us imagining it to be anything else but fire, though of a peculiar kind; in other words it is light, which he distinguishes from flame as being only modestly warm: this light is a corporeal substance but from it there shines forth that other "light" which, though it carries the same name, we pronounce incorporeal, given forth from the first as its flower and radiance, the veritable "incandescent body." Plato's word earthy is commonly taken in too depreciatory a sense: he is thinking of earth as the principle of solidity; we are apt to ignore his distinctions and think of the concrete clay.

Fire of this order, giving forth this purest light, belongs to the upper realm, and there its seat is fixed by nature; but we must not, on that account, suppose the flame of earth to be associated with the beings of that higher sphere.

No: the flame of this world, once it has attained a certain height, is extinguished by the currents of air opposed to it. Moreover, as it carries an earthy element on its upward path, it is weighed downwards and cannot reach those loftier regions. It comes to a stand somewhere below the moon- making the air at that point subtler- and its flame, if any flame can persist, is subdued and softened, and no longer retains its first intensity, but gives out only what radiance it reflects from the light above.

And it is that loftier light- falling variously upon the stars; to each in a certain proportion- that gives them their characteristic differences, as well in magnitude as in colour; just such light constitutes also the still higher heavenly bodies which, however, like clear air, are invisible because of the subtle texture and unresisting transparency of their material substance and also by their very distance.

(508) Neither sight nor the eye in which sight resides is the sun? No. Yet of all the organs of sense the eye is the most like the sun? By far the most like. And the power which the eye possesses is a sort of effluence which is dispensed from the sun? Exactly. Then the sun is not sight, but the author of sight who is recognised by sight? True, he said. And this is he whom I call the child of the good, whom the good begat in his own likeness, to be in the visible world, in relation to sight and the things of sight, what the good is in the intellectual world in relation to mind and the things of mind: Will you be a little more explicit? he said. Why, you know, I said, that the eyes, when a person directs them towards objects on which the light of day is no longer shining, but the moon and stars only, see dimly, and are nearly blind; they seem to have no clearness of vision in them? Very true. But when they are directed towards objects on which the sun shines, they see clearly and there is sight in them? Certainly. And the soul is like the eye: when resting upon that on which truth and being shine, the soul perceives and understands, and is radiant with intelligence; but when turned towards the twilight of becoming and perishing, then she has opinion only, and goes blinking about, and is first of one opinion and then of another, and seems to have no intelligence? Just so.

(6) We may now consider the question whether fire is the sole element existing in that celestial realm and whether there is any outgoing thence with the consequent need of renewal.

Timaeus pronounced the material frame of the All to consist primarily of earth and fire for visibility, earth for solidity- and deduced that the stars must be mainly composed of fire, but not solely since there is no doubt they are solid.

And this is probably a true account. Plato accepts it as indicated by all the appearances. And, in fact, to all our perception- as we see them and derive from them the impression of illumination- the stars appear to be mostly, if not exclusively, fire: but on reasoning into the matter we judge that since solidity cannot exist apart from earth-matter, they must contain earth as well.

But what place could there be for the other elements? It is impossible to imagine water amid so vast a conflagration; and if air were present it would be continually changing into fire.

Admitting that two self-contained entities, standing as extremes to each other need for their coherence two intermediaries; we may still question whether this holds good with regard to physical bodies. Certainly water and earth can be mixed without any such intermediate. It might seem valid to object that the intermediates are already present in the earth and the water; but a possible answer would be, "Yes, but not as agents whose meeting is necessary to the coherence of those extremes."

None the less we will take it that the coherence of extremes is produced by virtue of each possessing all the intermediates. It is still not proven that fire is necessary to the visibility of earth and earth to the solidarity of fire.

On this principle, nothing possesses an essential-nature of its very own; every several thing is a blend, and its name is merely an indication of the dominant constituent.

Thus we are told that earth cannot have concrete existence without the help of some moist element- the moisture in water being the necessary adhesive- but admitting that we so find it, there is still a contradiction in pretending that any one element has a being of its own and in the same breath denying its self-coherence, making its subsistence depend upon others, and so, in reality, reducing the specific element to nothing. How can we talk of the existence of the definite Kind, earth- earth essential- if there exists no single particle of earth which actually is earth without any need of water to secure its self-cohesion? What has such an adhesive to act upon if there is absolutely no given magnitude of real earth to which it may bind particle after particle in its business of producing the continuous mass? If there is any such given magnitude, large or small, of pure earth, then earth can exist in its own nature, independently of water: if there is no such primary particle of pure earth, then there is nothing whatever for the water to bind. As for air- air unchanged, retaining its distinctive quality- how could it conduce to the subsistence of a dense material like earth?

Similarly with fire. No doubt Timaeus speaks of it as necessary not to the existence but to the visibility of earth and the other elements; and certainly light is essential to all visibility- we cannot say that we see darkness, which implies, precisely, that nothing is seen, as silence means nothing being heard.

But all this does not assure us that the earth to be visible must contain fire: light is sufficient: snow, for example, and other extremely cold substances gleam without the presence of fire- though of course it might be said that fire was once there and communicated colour before disappearing.

As to the composition of water, we must leave it an open question whether there can be such a thing as water without a certain proportion of earth.

But how can air, the yielding element, contain earth?

Fire, again: is earth perhaps necessary there since fire is by its own nature devoid of continuity and not a thing of three dimensions?

Supposing it does not possess the solidity of the three dimensions, it has that of its thrust; now, cannot this belong to it by the mere right and fact of its being one of the corporeal entities in nature? Hardness is another matter, a property confined to earth-stuff. Remember that gold- which is water- becomes dense by the accession not of earth but of denseness or consolidation: in the same way fire, with Soul present within it, may consolidate itself upon the power of the Soul; and there are living beings of fire among the Celestials.

But, in sum, do we abandon the teaching that all the elements enter into the composition of every living thing?

For this sphere, no; but to lift clay into the heavens is against nature, contrary to the laws of her ordaining: it is difficult, too, to think of that swiftest of circuits bearing along earthly bodies in its course nor could such material conduce to the splendour and white glint of the celestial fire.

(2) If sight depends upon the linking of the light of vision with the light leading progressively to the illumined object, then, by the very hypothesis, one intervening substance, the light, is indispensable: but if the illuminated body, which is the object of vision, serves as an agent operating certain changes, some such change might very well impinge immediately upon the eye, requiring no medium; this all the more, since as things are the intervening substance, which actually does exist, is in some degree changed at the point of contact with the eye .

Those who have made vision a forth-going act need not postulate an intervening substance- unless, indeed, to provide against the ray from the eye failing on its path- but this is a ray of light and light flies straight. Those who make vision depend upon resistance are obliged to postulate an intervening substance.

The champions of the image, with its transit through a void, are seeking the way of least resistance; but since the entire absence of intervenient gives a still easier path they will not oppose that hypothesis.

So, too, those that explain vision by sympathy must recognize that an intervening substance will be a hindrance as tending to check or block or enfeeble that sympathy; this theory, especially, requires the admission that any intervenient, and particularly one of kindred nature, must blunt the perception by itself absorbing part of the activity. Apply fire to a body continuous through and through, and no doubt the core will be less affected than the surface: but where we are dealing with the sympathetic parts of one living being, there will scarcely be less sensation because of the intervening substance, or, if there should be, the degree of sensation will still be proportionate to the nature of the separate part, with the intervenient acting merely 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.

(1) We undertook to discuss the question whether sight is possible in the absence of any intervening medium, such as air or some other form of what is known as transparent body: this is the time and place.

It has been explained that seeing and all sense-perception can occur only through the medium of some bodily substance, since in the absence of body the soul is utterly absorbed in the Intellectual Sphere. Sense-perception being the gripping not of the Intellectual but of the sensible alone, the soul, if it is to form any relationship of knowledge, or of impression, with objects of sense, must be brought in some kind of contact with them by means of whatever may bridge the gap.

The knowledge, then, is realized by means of bodily organs: through these, which are almost of one growth with it, being at least its continuations, it comes into something like unity with the alien, since this mutual approach brings about a certain degree of identity .

Admitting, then, that some contact with an object is necessary for knowing it, the question of a medium falls to the ground in the case of things identified by any form of touch; but in the case of sight- we leave hearing over for the present- we are still in doubt; is there need of some bodily substance between the eye and the illumined object?

No: such an intervening material may be a favouring circumstance, but essentially it adds nothing to seeing power. ! Dense bodies, such as clay, actually prevent sight; the less material the intervening substance is, the more clearly we see; the intervening substance, then, is a hindrance, or, if not that, at least not a help.

It will be objected that vision implies that whatever intervenes between seen and seer must first experience the object and be, as it were, shaped to it; we will be reminded that anyone facing to the object from the side opposite to ourselves sees it equally; we will be asked to deduce that if all the space intervening between seen and seer did not carry the impression of the object we could not receive it.

But all the need is met when the impression reaches that which is adapted to receive it; there is no need for the intervening space to be impressed. If it is, the impression will be of quite another order: the rod between the fisher's hand and the torpedo fish is not affected in the same way as the hand that feels the shock. And yet there too, if rod and line did not intervene, the hand would not be affected- though even that may be questioned, since after all the fisherman, we are told, is numbed if the torpedo merely lies in his net.

The whole matter seems to bring us back to that sympathy of which we have treated. If a certain thing is of a nature to be sympathetically affected by another in virtue of some similitude between them, then anything intervening, not sharing in that similitude, will not be affected, or at least not similarly. If this be so, anything naturally disposed to be affected will take the impression more vividly in the absence of intervening substance, even of some substance capable, itself, of being affected.