The perception of reality does not obtain the full value of knowledge, except when once socialised, once made the common property of men, and thereby also tested and verified.

There is one means only of doing that; viz. to analyse it into manageable and portable concepts. By language I mean the product of this conceptualisation. Thus language is necessary; for we must always speak, were it only to utter the impotence of words. Not less necessary is a critique of spontaneous language, of the laws which govern it, of the postulates which it embraces, of the methods which convey its implicit doctrines. Synthetic forms are actually theories already; they effect an adaptation of reality to the demands of practical use. If it is impossible to escape them, it is at least fitting not to employ them except with due knowledge, and when properly warned against the illusion of the false problems which they might arouse.

Let us first of all consider thought in itself, in its concrete life. What are the principal characteristics, the essential steps? We readily say, analysis and synthesis.

Nothing can be known except in contrast, correlation, or negation of another thing; and the act of knowledge, considered in itself, is unification. Thus number appears as a fundamental category, as an absolute condition of intelligibility; some go so far as to regard atomism as a necessary method. But that is inexact. No doubt the use of number and the resulting atomism are imposed by definition, we might say, on the thought which proceeds by conceptual analysis, and then by unifying construction; that is to say, on synthetic thought. But, in greater depth, thought is dynamic continuity and duration. Its essential work does not consist in discerning and afterwards in assembling ready-made elements. Let us see in it rather a kind of creative maturation, and let us attempt to grasp the nature of this causal activity. (H. Bergson, "Intellectual Effort" in the "Philosophical Review", January 1902.)

The act of thought is always a complex play of moving representations, an evolution of life in which incessant inner reactions occur. That is to say, it is movement. But there are several planes of thought, from intuition to language, and we must distinguish between the thought which moves on the surface among terms displayed on a single plane, and the thought with goes deeper and deeper from one plane to another.

We do not think solely by concepts or images; we think, first of all, according to Mr Bergson's expression, by dynamic schemes. What is a dynamic scheme? It is motive rather than representative, inexpressible in itself, but a source of language containing not so much the images or concepts in which it will develop as the indication of the path to be followed in order to obtain them. It is not so much system as movement, progress, genesis; it does not mark the gaze directed upon the various points of one plane of deliberate contemplation so much as an effort to pass through successive planes of thought in a direction leading from intuition to analysis. We might define it by its function of calling up images and concepts, representations which, for one and the same scheme, are neither strictly determined nor anything in particular in themselves, concurrent representations which have in common one and the same logical power.

The representations called up form a body to the scheme, and the relation of the scheme to the concepts and images which it calls up resembles, mutatis mutandis, the relation pointed out by Mr Bergson between an idea and its basis in the brain. In short, it is the very act of creative thought which the dynamic scheme interprets, the act not yet fixed in "results."

Nothing is easier than to illustrate the existence of this scheme. Let us merely remark a few facts of current observation. Recall, for example, the suggestive anxiety we experience when we seek to remember a name; the precise syllables of the name still escape us, but we feel them approaching, and already we possess something of them, since we immediately reject those which do not answer to a certain direction of expectancy; and by endeavouring to secure a more intimate feeling of this direction we suddenly arouse the desired recollection.

In the same way, what does it mean to have the sense of a complex situation in active life, if not that we perceive it, not as a static group of explicit details, but as a meeting of powers allied or hostile, convergent or divergent, directed towards this or that, of which the aggregate whole tends of itself to awaken in us the initial reactions which analyse it?

In the same way again, how do we learn, how can we assimilate a vast system of conceits or images? Our task is not to concentrate an enumerative attention on each individual factor; we should never get away from them, the weight would be too heavy.

What we entrust to memory is really a dynamic scheme permitting us to "regain" what we should not have succeeded in "retaining." In reality our only "knowledge" is through such a scheme, which contains in the state of potential implication an inexhaustible multiplicity ready to be developed in actual representations.

How, finally, is any discovery made? Finding is solving a problem; and to solve a problem we must always begin by supposing it solved. But of what does such a hypothesis consist?

It is not an anticipated view of the solution, for then all would be at an end; nor is it a simple formula putting in the present indicative what the enunciation expressed in the future or the imperative, for then nothing would be begun. It is exactly a dynamic scheme; that is to say, a method in the state of directed tension; and often, the discovery once realised as theory or system, capable of unending developments and resurrections, remains by the best of itself a method and a dynamic scheme.

But one last example will perhaps reveal the truth still more. "Anyone who has attempted literary composition knows well that when the subject has been long studied, all the documents collected, all the notes taken, we need, to embark on the actual work of composition, something more, an effort, often very painful, to place oneself suddenly in the very heart of the subject, and to seek as deep down as possible an impulse to which afterwards we shall only have to let ourselves go. This impulse, once received, projects the mind on a road where it finds both the information which it had collected and a thousand other details as well; it develops and analyses itself in terms, the enumeration of which would have no end; the further we advance, the more we discover; we shall never succeed in saying everything; and yet, if we turn sharply round towards the impulse we feel behind ourselves, to grasp it, it escapes; for it was not a thing but a direction of movement, and though indefinitely extensible, it is simplicity itself." (H. Bergson, "Metaphysical and Moral Review", January 1903. The whole critique of language is implicitly contained in this "Introduction to Metaphysics".)

The thought, then, which proceeds from one representation to another in one and the same plane is one kind; that which follows one and the same conceptual direction through descending planes is another. Creative and fertile thought is the thought which adopts the second kind of work. The ideal is a continual oscillation from one plane to the other, a restless alternative of intuitive concentration and conceptual expansion. But our idleness takes exception to this, for the feeling of effort appears precisely in the traject from the dynamic scheme to the images and concepts, in the passing from one plane of thought to another.

Thus the natural tendency is to remain in the last of these planes, that of language. We know what dangers threaten us there.

Suppose we have some idea or other and the word representing it. Do not suppose that to this word there is one corresponding sense only, nor even a finished group of various distinct and rigorously separable senses. On the contrary, there is a whole scale corresponding, a complete continuous spectrum of unstable meanings which tend unceasingly to resolve into one another. Dictionaries attempt to illuminate them. The task is impossible. They co-ordinate a few guiding marks; but who shall say what infinite transitions underlie them?

A word designates rather a current of thought than one or several halts on a logical path. Here again a dynamic continuity exists previous to the parcelling out of the acceptations. What, then, should be the attitude of the mind?

A supple moving attitude more attentive to the curve of change than to the possible halting-points along the road. But this is not the case at all; the effort would be too great, and what happens, on the contrary, is this. For the spectrum a chromatic scale of uniform tints is very quickly substituted. This is in itself an undesirable simplification, for it is impossible to reconstitute the infinity of real shades by combinations of fundamental colours each representing the homogeneous shore, which each region of the spectrum finally becomes.

However cleverly we proportion these averages, we get, at most, some vulgar counterfeit: orange, for example, is not a mixture of yellow and red, although this mixture may recall to those who have known it elsewhere the simple and original sensation of orange. Again, a second simplification, still more undesirable, succeeds the first.

There are no longer any colours at all; black lines serve as guide-marks. We are therefore with pure concepts decidedly in full symbolism. And it is with symbols that we shall henceforward be trying to reconstruct reality.

I need not go back to the general characteristics or the inconveniences of this method. Concepts resemble photographic views; concrete thickness escapes them. However exact, varied, or numerous we suppose them, they can certainly recall their object, but not reveal it to any one who had not had any direct intuition of it. Nothing is easier than to trace the plan of a body in four dimensions; all the same, this drawing does not admit "visualisation in space" as is the case with ordinary bodies, for want of a previous intuition which it would awaken: thus it is with concepts in relation to reality. Like photographs and like plans, they are extracted from reality, but we are not able to say that they were contained in it; and many of them besides are not so much as extracts; they are simple systematised notes, in fact, notes made upon notes. In other terms, concepts do not represent pieces, parts, or elements of reality. Literally they are nothing but simple symbolic notations. To wish to make integral factors of them would be as strange an illusion as that of seeing in the co-ordinates of a geometric point the constitutive essence of that point.

We do not make things with symbols, any more than we should reconstruct a picture with the qualifications which classify it.

Whence, then, comes the natural inclination of thought towards the concept? From the fact that thought delights in artifices which facilitate analysis and language.

The first of these artifices is that from which results the possibility of decomposition or recomposition according to arbitrary laws. For that we need a previous substitution of symbols for things. Nothing demonstrates this better than the celebrated arguments which we owe to Zeno of Elea. Mr Bergson returns to the discussion of them over and over again. ("Essay on the Immediate Data", pages 85-86; "Matter and Memory", pages 211-213, "Creative Evolution", pages 333-337.)

The nerve of the reasoning there consists in the evident absurdity there would be in conceiving an inexhaustible exhausted, an unachievable achieved; in short, a total actually completed, and yet obtained by the successive addition of an infinite number of terms.

But the question is to know whether a movement can be considered as a numerical multiplicity. Virtual divisibility there is, no doubt, but not actual division; divisibility is indefinite, whereas an actual division, if it respects the inner articulations of reality, is bound to halt at a limited number of phases.

What we divide and measure is the track of the movement once accomplished, not the movement itself: it is the trajectory, not the traject. In the trajectory we can count endless positions; that is to say, possible halts. Let us not suppose that the moving body meets these elements all ready-marked. Hence what the Eleatic dialectic illustrates is a case of incommensurability; the radical inability of analysis to end a certain task; our powerlessness to explain the fact of the transit, if we apply to it such and such modes of numerical decomposition or recomposition, which are valid only for space; the impossibility of conceiving becoming as susceptible of being cut up into arbitrary segments, and afterwards reconstructed by summing of terms according to some law or other; in short, it is the nature of movement, which is without division, number, or concept.

But thought delights in analyses regulated by the sole consideration of easy language; hence its tendency to an arithmetic and geometry of concepts, in spite of the disastrous consequences; and thus the Eleatic paradox is no less instructive in its specious character than in the solution which it embodies.

At bottom, natural thought, I mean thought which abandons itself to its double inclination of synthetic idleness and useful industry, is a thought haunted by anxieties of the operating manual, anxieties of fabrication.

What does it care about the fluxes of reality and dynamic depths? It is only interested in the outcrops scattered here and there over the firm soil of the practical, and it solidifies "terms" like stakes plunged in a moving ground. Hence comes the configuration of its spontaneous logic to a geometry of solids, and hence come concepts, the instantaneous moments taken in transitions.

Scientific thought, again, preserves the same habits and the same preferences. It seeks only what repeats, what can be counted. Everywhere, when it theorises, it tends to establish static relations between composing unities which form a homogeneous and disconnected multiplicity.

Its very instruments bias it in that direction. The apparatus of the laboratory really grasps nothing but arrangement and coincidence; in a word, states not transitions. Even in cases of contrary appearance, for example, when we determine a weight by observing the oscillation of a balance and not its rest, we are interested in regular recurrence, in a symmetry, in something therefore which is of the nature of an equilibrium and a fixity all the same. The reason of it is that science, like common-sense, although in a manner a little different, aims only in actual fact at obtaining finished and workable results.

Let us imagine reality under the figure of a curve, a rhythmic succession of phases of which our concepts mark so many tangents. There is contact at one point, but at one point only. Thus our logic is valid as infinitesimal analysis, just as the geometry of the straight line allows us to define each state of curve. It is thus, for example, that vitality maintains a relation of momentary tangency to the physico-chemical structure. If we study this relation and analogous relations, this fact remains indisputably legitimate. Let us not think, however, that such a study, even when repeated in as many points as we wish, can ever suffice.

We must afterwards by genuine integration attain moving continuity. That is exactly the task represented by the return to intuition, with its proper instrument, the dynamic scheme. From this tangential point of view we try to grasp the genesis of the curve as envelope, or rather, and better still, the birth of successive tangents as instantaneous directions. Speaking non-metaphorically, we cling to genetic methods of conceptualisation and proceed from the generating principle to its conceptual derivatives.

But our thought finds it very difficult to sustain such an effort long. It is partial to rectilineal deduction, actual becoming horrifies it. It desires immediately to find "things" sharply determined and very clear. That is why immediately a tangent is constructed, it follows its movement in a straight line to infinity. Thus are produced limit-concepts, the ultimate terms, the atoms of language. As a rule they go in pairs, in antithetic couples, every analysis being dichotomy, since the discernment of one path of abstraction determines in contrast, as a complementary remainder, the opposite path of direction. Hence, according to the selection effected among concepts, and the relative weight which is attributed to them, we get the antinomies between which a philosophy of analysis must for ever remain oscillating and torn in sunder. Hence comes the parcelling up of metaphysics into systems, and its appearance of regulated play "between antagonistic schools which get up on the stage together, each to win applause in turn." (H. Bergson, "Report of the French Philosophical Society", meeting, 2nd May 1901.)

The method followed to find a genuine solution must be inverse; not dialectic combination of pre-existing concepts, but, setting out from a direct and really lived intuition, a descent to ever new concepts along dynamic schemes which remain open. From the same intuition spring many concepts: "As the wind which rushes into the crossroads divides into diverging currents of air, which are all only one and the same gust." ("Creative Evolution", page 55.)

The antinomies are resolved genetically, whilst in the plane of language they remain irreducible. With a heterogeneity of shades, when we mix the tints and neutralise them by one another, we easily create homogeneity; but take the result of this work, that is to say, the average final colour, and it will be impossible to reconstitute the wealth of the original.

Do you desire a precise example of the work we must accomplish? Take that of change; (Cf. two lectures delivered by Mr Bergson at Oxford on "The Perception of Change", 26th and 27th May 1911.) no other is more significant or clearer. It shows us two necessary movements in the reform of our habits of imagination or conception.

Let us try first of all to familiarise ourselves with the images which show us the fixity deriving from becoming.

Two colliding waves, two rollers meeting, typify rest by extinction and interference. With the movement of a stone, and the fluidity of running water, we form the instantaneous position of a ricochet. The very movement of the stone, seen in the successive positions of the tangent to the trajectory, is stationary to our view.

What is dynamic stability, except non-variation arising from variation itself? Equilibrium is produced from speed. A man running solidifies the moving ground. In short, two moving bodies regulated by each other become fixed in relation to each other.

After this, let us try to perceive change in itself, and then represent it to ourselves according to its specific and original nature.

The common conception needs reform on two principal points:

(1) All change is revealed in the light of immediate intuition, not as a numerical series of states, but a rhythm of phases, each of which constitutes an indivisible act, in such a way that each change has its natural inner articulations, forbidding us to break it up according to arbitrary laws, like a homogeneous length.

(2) Change is self-sufficient; it has no need of a support, a moving body, a "thing" in motion. There is no vehicle, no substance, no spatial receptacle, resembling a theatre-scene, no material dummy successively draped in coloured stuffs; on the contrary, it is the body or the atom which should be subordinately defined as symbols of completed becoming.

Of movement thus conceived, indivisible and substantial, what better image can we have than a musical evolution, a phrase in melody? That is how we must work to conceive reality. If such a conception at first appears obscure, let us credit experience, for ideas are gradually illuminated by the very use we make of them, "the clarity of a concept being hardly anything, at bottom, but the assurance once obtained that we can handle it profitably." (H. Bergson, "Introduction to Metaphysics".)

If we require to reach a conception of this kind with regard to change, the Eleatic dialectic is there to establish it beyond dispute, and positive science comes to the same conclusion, since it shows us everywhere nothing but movements placed upon movements, never fixed "things," except as temporary symbols of what we leave at a given moment outside the field of study.

In any case, the difficulty of such a conception need not stop us; it is little more than a difficulty of the imaginative order. And as for the conception itself, or rather the corresponding intuition, it will share the fate of all its predecessors: to our contemporaries it will be a scandal, a century later a stroke of genius, after some centuries common evidence, and finally an instinctive axiom.