(13) It has been remarked that the continuous is effectually distinguished from the discrete by their possessing the one a common, the other a separate, limit.

The same principle gives rise to the numerical distinction between odd and even; and it holds good that if there are differentiae found in both contraries, they are either to be abandoned to the objects numbered, or else to be considered as differentiae of the abstract numbers, and not of the numbers manifested in the sensible objects. If the numbers are logically separable from the objects, that is no reason why we should not think of them as sharing the same differentiae.

But how are we to differentiate the continuous, comprising as it does line, surface and solid? The line may be rated as of one dimension, the surface as of two dimensions, the solid as of three, if we are only making a calculation and do not suppose that we are dividing the continuous into its species; for it is an invariable rule that numbers, thus grouped as prior and posterior, cannot be brought into a common genus; there is no common basis in first, second and third dimensions. Yet there is a sense in which they would appear to be equal- namely, as pure measures of Quantity: of higher and lower dimensions, they are not however more or less quantitative.

Numbers have similarly a common property in their being numbers all; and the truth may well be, not that One creates two, and two creates three, but that all have a common source.

Suppose, however, that they are not derived from any source whatever, but merely exist; we at any rate conceive them as being derived, and so may be assumed to regard the smaller as taking priority over the greater: yet, even so, by the mere fact of their being numbers they are reducible to a single type.

What applies to numbers is equally true of magnitudes; though here we have to distinguish between line, surface and solid- the last also referred to as "body"- in the ground that, while all are magnitudes, they differ specifically.

It remains to enquire whether these species are themselves to be divided: the line into straight, circular, spiral; the surface into rectilinear and circular figures; the solid into the various solid figures- sphere and polyhedANSWER: whether these last should be subdivided, as by the geometers, into those contained by triangular and quadrilateral planes: and whether a further division of the latter should be performed.

(10) Another method of division is possible: substances may be classed as hot-dry, dry-cold, cold-moist, or however we choose to make the coupling. We may then proceed to the combination and blending of these couples, either halting at that point and going no further than the compound, or else subdividing by habitation- on the earth, in the earth- or by form and by the differences exhibited by living beings, not qua living, but in their bodies viewed as instruments of life.

Differentiation by form or shape is no more out of place than a division based on qualities- heat, cold and the like. If it be objected that qualities go to make bodies what they are, then, we reply, so do blendings, colours, shapes. Since our discussion is concerned with Sensible Substance, it is not strange that it should turn upon distinctions related to sense-perception: this Substance is not Being pure and simple, but the Sensible Being which we call the Universe.

We have remarked that its apparent subsistence is in fact an assemblage of Sensibles, their existence guaranteed to us by sense-perception. But since their combination is unlimited, our division must be guided by the Form-Ideas of living beings, as for example the Form-Idea of Man implanted in Body; the particular Form acts as a qualification of Body, but there is nothing unreasonable in using qualities as a basis of division.

We may be told that we have distinguished between simple and composite bodies, even ranking them as opposites. But our distinction, we reply, was between material and organic bodies and raised no question of the composite. In fact, there exists no means of opposing the composite to the simple; it is necessary to determine the simples in the first stage of division, and then, combining them on the basis of a distinct underlying principle, to differentiate the composites in virtue of their places and shapes, distinguishing for example the heavenly from the earthly.

These observations will suffice for the Being , or rather the Becoming, which obtains in the Sensible realm.

(527) Yes, that is what we assert. Yet anybody who has the least acquaintance with geometry will not deny that such a conception of the science is in flat contradiction to the ordinary language of geometricians. How so? They have in view practice only, and are always speaking, in a narrow and ridiculous manner, of squaring and extending and applying and the like—they confuse the necessities of geometry with those of daily life; whereas knowledge is the real object of the whole science. Certainly, he said. Then must not a further admission be made? What admission? That the knowledge at which geometry aims is knowledge of the eternal, and not of aught perishing and transient. That, he replied, may be readily allowed, and is true. Then, my noble friend, geometry will draw the soul towards truth, and create the spirit of philosophy, and raise up that which is now unhappily allowed to fall down. Nothing will be more likely to have such an effect. Then nothing should be more sternly laid down than that the inhabitants of your fair city should by all means learn geometry. Moreover the science has indirect effects, which are not small. Of what kind? he said. There are the military advantages of which you spoke, I said; and in all departments of knowledge, as experience proves, any one who has studied geometry is infinitely quicker of apprehension than one who has not. Yes indeed, he said, there is an infinite difference between them. Then shall we propose this as a second branch of knowledge which our youth will study? Let us do so, he replied.

(510) sphere of the visible consists of images. And by images I mean, in the first place, shadows, and in the second place, reflections in water and in solid, smooth and polished bodies and the like: Do you understand? Yes, I understand. Imagine, now, the other section, of which this is only the resemblance, to include the animals which we see, and everything that grows or is made. Very good. Would you not admit that both the sections of this division have different degrees of truth, and that the copy is to the original as the sphere of opinion is to the sphere of knowledge? Most undoubtedly. Next proceed to consider the manner in which the sphere of the intellectual is to be divided. In what manner? Thus:—There are two subdivisions, in the lower of which the soul uses the figures given by the former division as images; the enquiry can only be hypothetical, and instead of going upwards to a principle descends to the other end; in the higher of the two, the soul passes out of hypotheses, and goes up to a principle which is above hypotheses, making no use of images 14 as in the former case, but proceeding only in and through the ideas themselves. I do not quite understand your meaning, he said. Then I will try again; you will understand me better when I have made some preliminary remarks. You are aware that students of geometry, arithmetic, and the kindred sciences assume the odd and the even and the figures and three kinds of angles and the like in their several branches of science; these are their hypotheses, which they and every body are supposed to know, and therefore they do not deign to give any account of them either to themselves or others;

(511) I understand, he said, that you are speaking of the province of geometry and the sister arts. And when I speak of the other division of the intelligible, you will understand me to speak of that other sort of knowledge which reason herself attains by the power of dialectic, using the hypotheses not as first principles, but only as hypotheses—that is to say, as steps and points of departure into a world which is above hypotheses, in order that she may soar beyond them to the first principle of the whole; and clinging to this and then to that which depends on this, by successive steps she descends again without the aid of any sensible object, from ideas, through ideas, and in ideas she ends. I understand you, he replied; not perfectly, for you seem to me to be describing a task which is really tremendous; but, at any rate, I understand you to say that knowledge and being, which the science of dialectic contemplates, are clearer than the notions of the arts, as they are termed, which proceed from hypotheses only: these are also contemplated by the understanding, and not by the senses: yet, because

(71) Magnitude is divided into two parts--magnitude which is stationary and magnitude which is movable, the stationary pare having priority. Multitude is also divided into two parts, for it is related both to itself and to other things, the first relationship having priority. Pythagoras assigned the science of arithmetic to multitude related to itself, and the art of music to multitude related to other things. Geometry likewise was assigned to stationary magnitude, and spherics (used partly in the sense of astronomy) to movable magnitude. Both multitude and magnitude were circumscribed by the circumference of mind. The atomic theory has proved size to be the result of number, for a mass is made up of minute units though mistaken by the uninformed for a single simple substance.

(14) How are we to classify the straight line? Shall we deny that it is a magnitude?

The suggestion may be made that it is a qualified magnitude. May we not, then, consider straightness as a differentia of "line"? We at any rate draw on Quality for differentiae of Substance.

The straight line is, thus, a quantity plus a differentia; but it is not on that account a composite made up of straightness and line: if it be a composite, the composite possesses a differentiae of its own.

But why is not the product of three lines included in Quantity? The answer is that a triangle consists not merely of three lines but of three lines in a particular disposition, a quadrilateral of four lines in a particular disposition: even the straight line involves disposition as well as quantity.

Holding that the straight line is not mere quantity, we should naturally proceed to assert that the line as limited is not mere quantity, but for the fact that the limit of a line is a point, which is in the same category, Quantity. Similarly, the limited surface will be a quantity, since lines, which have a far better right than itself to this category, constitute its limits. With the introduction of the limited surface- rectangle, hexagon, polygon- into the category of Quantity, this category will be brought to include every figure whatsoever.

If however by classing the triangle and the rectangle as qualia we propose to bring figures under Quality, we are not thereby precluded from assigning the same object to more categories than one: in so far as it is a magnitude- a magnitude of such and such a size- it will belong to Quantity; in so far as it presents a particular shape, to Quality.

It may be urged that the triangle is essentially a particular shape. Then what prevents our ranking the sphere also as a quality?

To proceed on these lines would lead us to the conclusion that geometry is concerned not with magnitudes but with Quality. But this conclusion is untenable; geometry is the study of magnitudes. The differences of magnitudes do not eliminate the existence of magnitudes as such, any more than the differences of substances annihilate the substances themselves.

Moreover, every surface is limited; it is impossible for any surface to be infinite in extent.

Again, when I find Quality bound up with Substance, I regard it as substantial quality: I am not less, but far more, disposed to see in figures or shapes varieties of Quantity. Besides, if we are not to regard them as varieties of magnitude, to what genus are we to assign them?

Suppose, then, that we allow differences of magnitude; we commit ourselves to a specific classification of the magnitudes so differentiated.

(54) Timaeus: and conversely, when many small bodies are resolved into their triangles they will produce, when unified, one single large mass of another Kind. So let thus much be declared concerning their generation into one another. In the next place we have to explain the form in which each Kind has come to exist and the numbers from which it is compounded. First will come that form which is primary and has the smallest components, and the element thereof is that triangle which has its hypotenuse twice as long as its lesser side. And when a pair of such triangles are joined along the line of the hypotenuse, and this is done thrice, by drawing the hypotenuses

(8) But we are digressing: we must resume our enquiry into the cause of dissimilarity among relations. Yet we must first be informed what reality, common to all cases, is possessed by this Existence derived from mutual conditions.

Now the common principle in question cannot be a body. The only alternative is that, if it does exist, it be something bodiless, either in the objects thus brought together or outside of them.

Further, if Relation always takes the same form, the term is univocal ; if not, that is if it differs from case to case, the term is equivocal, and the same reality will not necessarily be implied by the mere use of the term Relation.

How then shall we distinguish relations? We may observe that some things have an inactive or dormant relation, with which their actuality is entirely simultaneous; others, combining power and function with their relation, have the relation in some mode always even though the mode be merely that of potentiality, but attain to actual being only in contact with their correlatives. Or perhaps all distinctions may be reduced to that between producer and product, where the product merely gives a name to the producer of its actuality: an example of this is the relation of father to son, though here both producer and product have a sort of actuality, which we call life.

Are we thus, then, to divide Relation, and thereby reject the notion of an identical common element in the different kinds of Relation, making it a universal rule that the relation takes a different character in either correlative? We must in this case recognise that in our distinction between productive and non-productive relations we are overlooking the equivocation involved in making the terms cover both action and passion, as though these two were one, and ignoring the fact that production takes a different form in the two correlatives. Take the case of equality, producing equals: nothing is equal without equality, nothing identical without identity. Greatness and smallness both entail a presence- the presence of greatness and smallness respectively. When we come to greater and smaller, the participants in these relations are greater and smaller only when greatness and smallness are actually observed in them.

(511) they start from hypotheses and do not ascend to a principle, those who contemplate them appear to you not to exercise the higher reason upon them, although when a first principle is added to them they are cognizable by the higher reason. And the habit which is concerned with geometry and the cognate sciences I suppose that you would term understanding and not reason, as being intermediate between opinion and reason. You have quite conceived my meaning, I said; and now, corresponding to these four divisions, let there be four faculties in the soul—reason answering to the highest, understanding to the second, faith (or conviction) to the third, and perception of shadows to the last—and let there be a scale of them, and let us suppose that the several faculties have clearness in the same degree that their objects have truth. I understand, he replied, and give my assent, and accept your arrangement.

(2) Now the reasoning faculty which undertakes this problem is not a unity but a thing of parts; it brings the bodily nature into the enquiry, borrowing its principles from the corporeal: thus it thinks of the Essential Existence as corporeal and as a thing of parts; it baulks at the unity because it does not start from the appropriate principles. We, however, must be careful to bring the appropriately convincing principles to the discussion of the Unity, of perfect Being: we must hold to the Intellectual principles which alone apply to the Intellectual Order and to Real Being.

On the one hand there is the unstable, exposed to all sorts of change, distributed in place, not so much Being as Becoming: on the other, there is that which exists eternally, not divided, subject to no change of state, neither coming into being nor falling from it, set in no region or place or support, emerging from nowhere, entering into nothing, fast within itself.

In dealing with that lower order we would reason from its own nature and the characteristics it exhibits; thus, on a plausible foundation, we achieve plausible results by a plausible system of deduction: similarly, in dealing with the Intellectual, the only way is to grasp the nature of the essence concerned and so lay the sure foundations of the argument, not forgetfully straying over into that other order but basing our treatment on what is essential to the Nature with which we deal.

In every entity the essential nature is the governing principle and, as we are told, a sound definition brings to light many even of the concomitants: where the essential nature is the entire being, we must be all the more careful to keep to that, to look to that, to refer all to that.

(28) We have already indicated that Activity and Passivity are to be regarded as motions, and that it is possible to distinguish absolute motions, actions, passions.

As for the remaining so-called genera, we have shown that they are reducible to those which we have posited.

With regard to the relative, we have maintained that Relation belongs to one object as compared with another, that the two objects coexist simultaneously, and that Relation is found wherever a substance is in such a condition as to produce it; not that the substance is a relative, except in so far as it constitutes part of a whole- a hand, for example, or head or cause or principle or element.

We may also adopt the ancient division of relatives into creative principles, measures, excesses and deficiencies, and those which in general separate objects on the basis of similarities and differences.

Our investigation into the kinds of Being is now complete.

(5) How then can a multitude of essential beings be really one?

Obviously either the one essence will be entire in all, or the many will rise from a one which remains unaltered and yet includes the one- many in virtue of giving itself, without self-abandonment, to its own multiplication.

It is competent thus to give and remain, because while it penetrates all things it can never itself be sundered: this is an identity in variety.

There is no reason for dismissing this explanation: we may think of a science with its constituents standing as one total, the source of all those various elements: again, there is the seed, a whole, producing those new parts in which it comes to its division; each of the new growths is a whole while the whole remains undiminished: only the material element is under the mode of part, and all the multiplicity remains an entire identity still.

It may be objected that in the case of science the constituents are not each the whole.

But even in the science, while the constituent selected for handling to meet a particular need is present actually and takes the lead, still all the other constituents accompany it in a potential presence, so that the whole is in every part: only in this sense is the whole science distinguished from the part: all, we may say, is here simultaneously effected: each part is at your disposal as you choose to take it; the part invites the immediate interest, but its value consists in its approach to the whole.

The detail cannot be considered as something separate from the entire body of speculation: so treated it would have no technical or scientific value; it would be childish divagation. The one detail, when it is a matter of science, potentially includes all. Grasping one such constituent of his science, the expert deduces the rest by force of sequence.

the geometrician, in his analysis, shows that the single proposition includes all the items that go to constitute it and all the propositions which can be developed from it.

It is our feebleness that leads to doubt in these matters; the body obscures the truth, but There all stands out clear and separate.

(4) If we had to ascertain the nature of body and the place it holds in the universe, surely we should take some sample of body, say stone, and examine into what constituents it may be divided. There would be what we think of as the substrate of stone, its quantity- in this case, a magnitude; its quality- for example, the colour of stone. As with stone, so with every other body: we should see that in this thing, body, there are three distinguishable characteristics- the pseudo-substance, the quantity, the quality- though they all make one and are only logically trisected, the three being found to constitute the unit thing, body. If motion were equally inherent in its constitution, we should include this as well, and the four would form a unity, the single body depending upon them all for its unity and characteristic nature.

The same method must be applied in examining the Intellectual Substance and the genera and first-principles of the Intellectual sphere.

But we must begin by subtracting what is peculiar to body, its coming-to-be, its sensible nature, its magnitude- that is to say, the characteristics which produce isolation and mutual separation. It is an Intellectual Being we have to consider, an Authentic Existent, possessed of a unity surpassing that of any sensible thing.

Now the wonder comes how a unity of this type can be many as well as one. In the case of body it was easy to concede unity-with-plurality; the one body is divisible to infinity; its colour is a different thing from its shape, since in fact they are separated. But if we take Soul, single, continuous, without extension, of the highest simplicity- as the first effort of the mind makes manifest- how can we expect to find multiplicity here too? We believed that the division of the living being into body and soul was final: body indeed was manifold, composite, diversified; but in soul we imagined we had found a simplex, and boldly made a halt, supposing that we had come to the limit of our course.

Let us examine this soul, presented to us from the Intellectual realm as body from the Sensible. How is its unity a plurality? How is its plurality a unity? Clearly its unity is not that of a composite formed from diverse elements, but that of a single nature comprising a plurality.

This problem attacked and solved, the truth about the genera comprised in Being will thereby, as we asserted, be elucidated also.

(14) To the argument touching relation we have an answer surely legitimate:

The Unity is not of a nature to lose its own manner of being only because something else stands in a state which it does not itself share; to stray from its unity it must itself suffer division into duality or the still wider plurality.

If by division the one identical mass can become a duality without loss of quantity, clearly the unity it possessed and by this destructive division lost was something distinct. What may be alternatively present and absent to the same subject must be classed among Real-Beings, regardless of position; an accidental elsewhere, it must have reality in itself whether it be manifested in things of sense or in the Intellectual- an accidental in the Laters but self-existent in the higher, especially in the First in its aspect of Unity developing into Being. We may be told that Unity may lose that character without change in itself, becoming duality by association with something else; but this is not true; unity does not become two things; neither the added nor what takes the addition becomes two; each remains the one thing it was; the duality is predicable of the group only, the unity remaining unchanged in each of those unchanged constituents.

Two and the Dyad are not essentially relative: if the only condition to the construction of duality were meeting and association such a relation might perhaps constitute Twoness and Duality; but in fact we see Duality produced by the very opposite process, by the splitting apart of a unity. This shows that duality- or any other such numerical form- is no relation produced either by scission or association. If one configuration produces a certain thing it is impossible that the opposite should produce the same so that the thing may be identified with the relation.

What then is the actual cause?

Unity is due to the presence of Unity; duality to that of Duality; it is precisely as things are white by Whiteness, just by Justice, beautiful by Beauty. Otherwise we must reject these universals and call in relation here also: justice would arise from a certain attitude in a given situation, Beauty from a certain pattern of the person with nothing present able to produce the beauty, nothing coming from without to effect that agreeable appearance.

You see something which you pronounce to be a unity; that thing possesses also size, form, and a host of other characteristics you might name; size, bulk, sweetness, bitterness and other Ideas are actually present in the thing; it surely cannot be thought that, while every conceivable quality has Real-Being, quantity has not and that while continuous quantity exists, discrete quantity does not and this though continuous quantity is measured by the discrete. No: as size by the presence of Magnitude, and Oneness by the presence of Unity, so with Duality and all the other numerical modes.

As to the How of participation, the enquiry is that of all participation in Ideal Forms; we must note, however, that the presence of the Decad in the looser totals is different from its presence in the continuous; there is difference again in its presence within many powers where multiplicity is concentred in unity; arrived at the Intellectuals, there too we discover Number, the Authentic Number, no longer entering the alien, Decad-Absolute not Decad of some particular Intellectual group.

(526) And indeed, you will not easily find a more difficult study, and not many as difficult. You will not. And, for all these reasons, arithmetic is a kind of knowledge in which the best natures should be trained, and which must not be given up. I agree. Let this then be made one of our subjects of education. And next, shall we enquire whether the kindred science also concerns us? You mean geometry? Exactly so. Clearly, he said, we are concerned with that part of geometry which relates to war; for in pitching a camp, or taking up a position, or closing or extending the lines of an army, or any other military manoeuvre, whether in actual battle or on a march, it will make all the difference whether a general is or is not a geometrician. Yes, I said, but for that purpose a very little of either geometry or calculation will be enough; the question relates rather to the greater and more advanced part of geometry— whether that tends in any degree to make more easy the vision of the idea of good; and thither, as I was saying, all things tend which compel the soul to turn her gaze towards that place, where is the full perfection of being, which she ought, by all means, to behold. True, he said. Then if geometry compels us to view being, it concerns us; if becoming only, it does not concern us?

(7) 5. “Whoever, therefore, is able to analyze all the genera which are contained under one and the same principle, and again to compose and con-numerate them, he appears to me to be the wisest of men, and to possess the most perfect veracity. Farther still, he will also have discovered a beautiful place of survey, from which it will be possible to behold divinity, and all things that are in co-ordination with, and successive to him, subsisting separately, or distinct from each other. Having likewise entered this most ample road, being impelled in a right direction by intellect, and having arrived at the end of his course, he will have conjoined beginnings with ends, and will know that God is the principle, middle, and end, of all things which are accomplished according to justice and right reason.”

(69) The Pythagoreans declared arithmetic to be the mother of the mathematical sciences. This is proved by the fact that geometry, music, and astronomy are dependent upon it but it is not dependent upon them. Thus, geometry may be removed but arithmetic will remain; but if arithmetic be removed, geometry is eliminated. In the same manner music depends upon arithmetic, but the elimination of music affects arithmetic only by limiting one of its expressions. The Pythagoreans also demonstrated arithmetic to be prior to astronomy, for the latter is dependent upon both geometry and music. The size, form, and motion of the celestial bodies is determined by the use of geometry; their harmony and rhythm by the use of music. If astronomy be removed, neither geometry nor music is injured; but if geometry and music be eliminated, astronomy is destroyed. The priority of both geometry and music to astronomy is therefore established. Arithmetic, however, is prior to all; it is primary and fundamental.

(4) But this science, this Dialectic essential to all the three classes alike, what, in sum, is it?

It is the Method, or Discipline, that brings with it the power of pronouncing with final truth upon the nature and relation of things- what each is, how it differs from others, what common quality all have, to what Kind each belongs and in what rank each stands in its Kind and whether its Being is Real-Being, and how many Beings there are, and how many non-Beings to be distinguished from Beings.

Dialectic treats also of the Good and the not-Good, and of the particulars that fall under each, and of what is the Eternal and what the not Eternal- and of these, it must be understood, not by seeming-knowledge but with authentic science.

All this accomplished, it gives up its touring of the realm of sense and settles down in the Intellectual Kosmos and there plies its own peculiar Act: it has abandoned all the realm of deceit and falsity, and pastures the Soul in the "Meadows of Truth": it employs the Platonic division to the discernment of the Ideal-Forms, of the Authentic-Existence and of the First-Kinds : it establishes, in the light of Intellection, the unity there is in all that issues from these Firsts, until it has traversed the entire Intellectual Realm: then, resolving the unity into the particulars once more, it returns to the point from which it starts.

Now rests: instructed and satisfied as to the Being in that sphere, it is no longer busy about many things: it has arrived at Unity and it contemplates: it leaves to another science all that coil of premisses and conclusions called the art of reasoning, much as it leaves the art of writing: some of the matter of logic, no doubt, it considers necessary- to clear the ground- but it makes itself the judge, here as in everything else; where it sees use, it uses; anything it finds superfluous, it leaves to whatever department of learning or practice may turn that matter to account.

(2) This mode of solution, therefore, is far superior, which does not suppose that divine works are effected through contrariety, or discrepance, in the way in which generated natures are usually produced; but asserts that every such work is rightly accomplished through sameness, union, and consent. Hence, if we separate from each other that which invokes and that which is invoked, that which commands and that which is commanded, that which is more and that which is less excellent, we shall, in a certain respect, transfer the contrariety of generations to the unbegotten goods of the Gods. But if we despise all such things, as it is just we should, as of an earth-born nature, and ascribe that which is common and simple, as being more honourable, to the powers who transcend the variety which is in the realms of generation, the first hypothesis of these questions will be immediately subverted, so that no reasonable doubt concerning them will be left.