ORGANIC PHYSICS. 29 those which relate to the species, especially when it is gregarious. With regard to Man, especially, this distinc- tion is fundamental. The last order of phenomena is evidently dependent on the first, and is more complex. Hence we have two great sections in organic physics — Physiology, properly so called, and Social Physics, which is dependent on it. In all ^' P'lysiology. Social phenomena we perceive the working 2 Sociolof-v of the physiological laws of the individual; and moreover something which modifies their effects, and which belongs to the influence of individuals over each other — singularly complicated in the case of the human race by the influence of generations on their successors. Thus it is clear that our social science must issue from that which relates to the life of the individual. On the other hand, there is no occasion to suppose, as some eminent physiologists have done, that Social Physics is only an appendage to physiology. The phenomena of the two are not identical, though they are homogeneous; and it is of high importance to hold the two sciences separate. As social conditions modify the operation of physiological laws, Social Physics must have a set of observations of its own.
It would be easy to make the divisions of the Organic half of Science correspond with those of the Inorganic, by dividing j^hysiology into vegetable and animal, according to popular custom. But this distinction, however im- portant in Concrete Physics (in that secondary and special class of studies before declared to be inappropriate to this wox'k), hardly extends into those Abstract Physics with which we have to do. Vegetables and animals come alike under our notice, when our object is to learn the general laws of life — that is, to study physiology. To say nothing of the fact that the distinction grows ever fainter and more dubious with new discoveries, it bears no relation to our plan of research; and we shall therefore consider that there is only one division in the science of organized bodies.
Thus we have before us Five fundamental Sciences in successive dependence, — Astro- gcien^*^^^''^ .nomy, Physics, Chemistry, Physiology, and 30 POSniVli PHILOSOPHY.
finally Social Physics. The first considers the most general, simple, abstract, and remote phenomena known to ns, and those which affect all others without being affected by them. The last considers the most particular, compound, concrete phenomena, and those which are the most interesting to Man. Between these two, the degrees of speciality, of complexity, and individuality are in regular proportion to the place of the respective sciences in the scale exhibited. Ti --n- f This — casting out everything arbitrary — we must regard as the true fihation ot the sciences; and in it we find the plan of this work.
. As we proceed, we shall find that the same their parts principle which gives this order to the whole body of science arranges the parts of each science; and its soundness will therefore be freshly attested us often as it presents itself afresh. There is no refusing a principle which distributes the interior of each science after the same method with the aggregate sciences. But this is not the place in which to do more than indicate what we shall contemplate more closely hereafter. We must now rapidly review some of the leading properties of the hierarchy of science that has been disclosed. Corroborations. This gradation is in essential conformity . with the order which has spontaneously lication follows taken place among the branches of natural the order of philosophy, when pursued separately, and disclosure of without any purposeof establishing such order, sciences. Such an accordance is a strong presumption that the arrangement is natural. Again, it coincides with the actual development of natural philosophy. If no lead- ing science can be effectually pursued otherwise than through those which precede it in the scale, it is evident that no vast development of any science could take place prior to the great astronomical discoveries to which we owe the impulse given to the whole. The progression may since have been simultaneous; but it has taken place in the order we have recognized.
This consideration is so important that it ro-eneousnS." i^ difiicult to understand without it the law which governs this history, as we have already seen, CLASSIFICATION CORROBORATED. 31 cannot be verified, unless we combine it with the scientific gradation just laid down: for it is according to this grada- tion that the different human theories have attained in succession the theological state, the metaphysical, and finally the positive. If we do not bear in mind the law which governs progression, we shall encounter insurmount- able difiiculties: for it is clear that the theological or meta- physical state of some fundamental theories must have temporarily coincided with the positive state of others which precede them in our established gradation, and actually have at times coincided with them; and this must involve the law itself in an obscurity which can be cleared up only by the classification we have proposed.
Again, this classification marks, with pre- 3. Marks rela- cision, the relative perfection of the different tive perfection sciences, which consists in the degree of pre- ^^ sciences, cision of knowledge, and in the relation of its different branches. It is easy to see that the more general, simple, and abstract any phenomena are, the less they depend on others, and the more jjrecise they are in themselves, and the more clear in their relations with each other. Thus, organic phenomena are less exact and systematic than inorganic; and of these again terrestrial are less exact and systematic than those of astronomy. This fact is completely accounted for by the gradation we have laid down; and we shall see as we proceed, that the possibility of applying mathematical analysis to the study of phenomena is exactly in proportion to the rank which they hold in the scale of the whole.
There is one liability to be guarded against, Defects are in which we may mention here. We must beware iis, not in of confounding the degree of precision which science. we are able to attain in regard to any science, with the cer- tainty of the science itself. The certainty of science, and our precision in the knowledge of it, are two very different things, which have been too often confounded; and are so still, though less than formerly. A very absurd proposition may be very precise; as if we should say, for instance, that the sum of the angles of a triangle is equal to three right angles; and a very certain proposition may be wanting in precision in our statement of it; as, for instance, when we 82 POSITIVE PHILOSOPHY.
assert that every man will die. If the different sciences offer to us a varying degree of precision, it is frona no want of certainty in themselves, but of our mastery of their phenomena.
The most interesting property of our Education formula of gradation is its effect on education, both general and scientific. This is its direct and unquestionable result. It will be more and more evident as we proceed, that no science can be effectually pursued without the preparation of a competent knowledge of the anterior sciences on which it depends. Physical ])hiloso])hers cannot understand Physics without at least a general knowledge of Astronomy; nor Chemists, without Physics and Astronomy; nor Physiologists, without Chemistry, Physics, and Astronomy; nor, above all, the students of Social philosophy, without a general knowledge of all the anterior sciences. As such conditions are, as yet, rarely fulfilled, and as no organization exists for their fulfilment, there is amongst us, in fact, no rational scientific education. To this may be attributed, in great part, the imperfection of even the most important sciences at this day. If the fact is so in regard to scientific education, it is no less striking in regard to general education. Our intellectual system cannot be renovated till the natural sciences are studied in their proper order. Even the highest understandings are apt to associate their ideas according to the order in which they were received: and it is only an intellect here and there, in any age, which in its utmost vigour can, like Bacon, Descartes, and Leibnitz, make a clearance in their field of knowledge, so as to reconstruct from the foundation their system of ideas.
Such is the operation of our great law Method upon scientific education through its effect on Doctrine. We cannot appreciate it duly without seeing how it affects Method.
As the phenomena which are homogeneous have been classed under one science, while those which belong to other sciences are heterogeneous, it follows that the Positive Method must be constantly modified in an uniform manner in the T-ange of the same fundamental science, and will luidergo modifications, different and more and more com- EFFECT ON METHOD. 33 pound, in passing from one science to another. Thus, under the scale laid down, we shall meet with it in all its varieties; which could not happen if we were to adopt a scale which should not fulfil the conditions we have ad- mitted. This is an all-important consideration; for if, as we have already seen, we cannot understand the positive method in the abstract, but only by its application, it is clear that we can have no adequate conception of it but by studying it in its varieties of application. Wo one science, however well chosen, could exhibit it. Though the Method is always the same, its j^rocedure is varied. For instance, it should be Observation with regard to one kind of phenomena, and Experiment with regard to another; and different kinds of experiment, according to the case. In the same way, a general precept, derived from one funda- mental science, however applicable to another, must have its spirit preserved by a reference to its origin; as in the case of the theory of Classifications. The best idea of the Positive Method would, of course, be obtained by the study of the most primitive and exalted of the sciences, if we were confined to one; but this isolated view would give no idea of its capacity of application to others in a modified form. Each science has its own proper advantages; and without some knowledge of them all, no conception can be formed of the power of the Method.
One more consideration must be briefly adverted to. It is necessary, not only to have o/sciences"*^ ^ a general knowledge of all the sciences, but to study them in their order. What can come of a study of complicated phenomena, if the student have not learned, by the contemplation of the simpler, what a Law is, what it is to Observe; what a Positive conception is; and even what a chain of 2*easoning is? Yet this is the way our young physiologists proceed every day, — plunging into the study of living bodies, without any other preparation than a knowledge of a dead language or two, or at most a super- ficial acquaintance with Physics and Chemistry, acquired without any philosophical method, or reference to any true point of departure in Natural philosophy. In the same way, with x'egard to Social phenomena, which are yet more complicated, what can be effected but by the rectification I. D 34 POSITIVE PHILOSOPHY, of tlie intellectnal iustrument, through an adequate study of the range of anterior phenomena? There are many who admit this: but they do not see how to set about the work, nor understand the Method itself, for want of the preparatory study; and thus, the admission remains barren, and social theories abide in the theological or metaphysical state, in spite of the efforts of those who believe themselves positive reformers.
These, then, are the four points of view under which Ave have recognized the importance of a Rational and Positive Classification.
AT..,.. r^.^r. It cannot but have been observed that in Mathematics...„.,.,, our enumeration of the sciences there is a prodigious omission. We have said nothing of Mathe- matical science. The omission was intentional; and the reason is no other than the vast importance of mathe- matics. This science will be the first of which we shall treat. Meantime, in order not to omit from our sketch a department so prominent, we may indicate here the general results of the study we are about to enter upon.
., In the present stage of our knowledge we '^ ' must regard Mathematics less as a constituent part of natural philosophy than as having been, since the .,. time of Descartes and Newton, the true basis of the whole of natural jihilosophy; though it is, exactly sj^eaking, both the one and the other. To us it is of less value for the knowledge of which it consists, substantial and valuable as that knowledge is, than as..., beinof the most powerful instrument that the human mind can employ m the investigation of the laws of natural phenomena.
In due precision, Mathematics must be science divided into two great sciences, quite distinct from each other — Abstract Mathematics, or the Calculus (taking the word in its most extended sense), and Concrete Mathematics, which is composed of General Geometry and of Rational Mechanics. The Concrete part is necessarily founded on the Abstract, and it becomes in its turn the basis of all natural philosophy; all the phenomena of the universe being regarded, as far as possible, as geometrical or mechanical.
MATHEMATICS A DOUBLE SCIENCE. 35 The Abstract portion is the only one which Abstract ma- is purely instrumental, it being simply an thematics an immense extension of natural logic to a cer- nistruinent. tain order of deductions. G-eometry and Concrete ma- mechanics must, on the contrary, be re- tlieniatics a garded as true natural sciences, founded, science, like all others, on observation, though, by the extreme simplicity of their phenomena, they can be systematized to much greater perfection. It is this capacity which has caused the experimental character of their first principles to be too much lost sight of. But these two physical sciences have this peculiarity, that they are now, and will be more and more, employed rather as method than as doctrine.
It needs scarcely be j^ointed out that in placing Mathe- matics at the head of Positive Philosophy, we are only ex- tending the application of the jsrincijile which has governed our whole Classification. We are simply carrying back our principle to its first manifestation. Geometrical and Mechani- cal phenomena are the most general, the most simple, the most abstract of all, — the most irreducible to others, the most independent of them; serving, in fact, as a basis to all others. It follows that the study of them is an indispen- sable preliminary to that of all others. Therefore must Mathematics hold the first place in the Mathematics hierarchy of the sciences, and be the point pre-eminent of departure of all Education, whether general ^" the scale. or special. In an empirical way, this has hitherto been the custom, — a custom which arose from the great antiquity of mathematical science. We now see why it must be renewed on a rational foundation.
We have now considered, in the form of a philosophical problem, the rational plan of the study of the Positive Philosophy. The order that results is this; an order which of all possible arrangements is the only one that accords with the natural manifestation of all phenomena. Mathematics, Astronomy, Physics, Chemistry, Physio- logy, Social Physics.
36 BOOK I.
MATHEMATICS.
CHAPTER I.
MATHEMATICS, ABSTRACT AND COKCRETE.
WE are now to enter upon the study of the first of the Six great Sciences; and we begin by establishing the importance of the Positive Philosophy in perfecting the character of each science in itself.
Though Mathematics is the most ancient and the most perfect science of all, the general idea of it is far from being clearly determined. The definition of the science, and its chief divisions, have remained up to this time vague and uncertain. The plural form of the name (grammati- cally used as singular) indicates the want of unity in its philosophical character, as commonly conceived. In fact, it is only since the beginning of the last century that it could be conceived of as a whole; and since that time geometers have been too much engaged on its different branches, and in apjjlying it to the most important laws of the universe, to have much attention left for the general system of the science. Now however the pursuit of its specialities is no longer so engrossing as to exclude us from the study of Mathematics in its unity. It has now reached a degree of consistency which admits of the effort to reduce its parts into a system, in preparation for further advance. The latest achievements of mathematicians have prepared the way for this by evidencing a character of unity in its principal parts which was not before known to exist. Such is eminently the sjiirit of the great author of the Theory of Eunctions and of Analytical Mechanics.
NATURE AND OBJECT OF MATHEMATICS. o7 The common description of Mathematics, „.. as the science of Magnitudes, or, somewhat niath"matics* more i^ositively, the science which relates to the Measurement of Mag7iitudes, is too vague and unmean- ing to have been used but for want of a better. Yet the idea contained in it is just at bottom, and is even suffi- ciently extensive, if proj^erly understood; but it needs precision and depth. It is important in such matters not to depart unnecessarily from notions generally admitted; and we will therefore see how, from this point of view, we can rise to such a definition of Mathematics as will be adequate to the importance, extent, and difficulty of the science.
Our first idea of measuring a magnitude r^-i ■ i. f is simply that of comparing the magnitude mathematics, in question with another supposed to be known, which is taken for the unit of comparison among all others of the same kind. Thus, when we define mathe- matics as being the measurement of magnitudes, we give a very imperfect idea of it, and one which seems to bear no relation, in this respect, to any science whatever. We seem to speak only of a series of mechanical procedures, like a superposition of lines, for obtaining the comparison of magnitudes, instead of a vast chain of reasonings, inex- haustible by the intellect. Nevertheless, this definition has no other fault than not being deep enough. It does not mistake the real aim of mathematics, but it presents as direct an object which is usually indirect; and thus it mis- leads us as to the nature of the science. To rectify this, we must attend to a general fact, which is easily estab- lished; that the direct measurement of a magnitude is often an impossible operation; so that if we had no other means of doing what we Avant, we must often forego the knowledge we desire. We can rarely even measure a right line by another right line; and this is the simplest measurement of all. The very first condition of this is that we should be able to traverse the line from one end to the other; and this cannot be done with the greater number of the distances which interest us the most. We cannot do it with the heavenly bodies, nor with the earth and any heavenly body, nor even with many distances on the earth; 38 POSITIVE PHILOSOPHY.
aud again, the length must be neither too great nor too small, and it must be conveniently situated; and a line which could be easily measured if it were horizontal be- comes impracticable if vertical. There are so few lines capable of being directly measured with precision, that we are compelled to resort to artificial lines, created to admit of a direct determination, aud to be the point of refei'ence for all others. If there is difficulty about the m.easurement of lines, the embarrassment is much greater when we have to deal with surfaces, volumes, velocities, times, forces, etc., and in general with all other magni- tudes susceptible of estimate, and, by their nature, difficult of direct measurement. It is the general fact of this diffi- culty, inherent in almost every case, which necessitates the formation of mathematical science; for, finding direct measurement so often impossible, we are compelled to devise means of doing it indirectly. Hence arose Mathe- matics.
. The general method employed, and the method only conceivable one, is to connect the magnitudes in question with some that can be directly determined, and thus to ascertain the former, through their relations with the latter. Such is the precise object of Mathematics, regarded as a whole. To form any- thing like a wortliy idea of it, we must remember that the indirect determination of magnitudes may have many degrees of indirectness. It often happens that the magni- tudes to which undetermined magnitudes are to be referred cannot themselves be measured directly, and must them- selves be made the subject of a prior process, and so on through a whole series; and thus, the mind is often obliged to establish a long course of intermediaries between the one aud the other point of the inquiry — points which may appear at the outset to have no connection whatever. -p., If this appears too abstract, it may become plain by a tew examples. In observmg a falling body, we are aware that two quantities are involved: the height from which the body falls, and the time occupied in its descent. These two quantities are connected, as they vary together, and together remain fixed. In the language of mathematicians, they are functions of each METHOD OF APPLICATION. 39 other. The measurement of one being impracticable, it is supplied by that of the other. By observing the time occupied by a stone in falling down a j^recipice, we can ascertain the height of the precipice as accurately as if we could measure it with a horizontal line. In another case, we may be able to know the height whence a body has fallen, and unable to observe the time with precision, and then we must have recourse to the inverse cjuestion, — to determine the time by the distance; as, for instance, if we were to inquire how long it would take for a body to fall from the moon. In these cases, the question is very simple, supposing we do not complicate it with considera- tions of intensity of gravity, resistance of a fluid medium, etc. But, to enlarge the question, we must contemplate the phenomenon in its greatest generality by supposing the fall to be oblique, and taking into account all the principal circumstances. Then, instead of two variable quantities, simply connected, the phenomenon will present a consider- able number, — the sjDace traversed, whether in a vertical or horizontal direction; the time employed in traversing it: the velocity of the body at each point of its course; and even the intensity and direction of the impulse which sent it forth; and finally, in some cases, the resistance of the medium, and the intensity of gravity. All these quantities are so connected that each in its turn may be determined indirectly by means of the others, and thus we shall have as many mathematical inquiries as there are magnitudes co-existing in the phenomenon considered. Such a very simple change as this in the physical conditions of a problem may place a mathematical question, originally quite elementary, in the rank of those difficult questions whose complete and rigorous solution transcends the power of the human understanding.
Again,— we may take a geometrical example. We want to determine a distance not directly measurable. We shall conceive of it as making a part of some ficjure, or system of lines of some soi't, of which the other parts are directly measurable; let us say a triangle (for this is the simplest, and to it all others are reducible). The distance in question is supposed to form a portion of a triangle, in which we are able to determine directly, either another 40 ' POSITIVE PHILOSOPHY, side and two angles, or two sides and one angle. The knowledge required is obtained by the mathematical labour of deducing the unknown distance from the ob- served elements, by means of the relation between them. The process may, and commonly does, become highly com- plicated by the elements supjDosed to be known being them- selves determinable only in an indirect manner, by the aid of fresh auxiliary systems, the number of which may be very considerable. The distance, once ascertained, will often enable us to obtain new quantities, which will offer occasion for new mathematical questions. Thus, when we once know the distance of any object, the observation, simple and always possible, of its apparent diameter, may disclose to us, with certainty, however indirectly, its real dimensions; and at length, by a series of analogous in- quiries, its surface, its volume, even its weight, and a mul- titude of other qualities which might have seemed out of the reach of our knowledge for ever. It is by such labours that Man has learned to know, not only the distances of the planets from the earth and from each other, but their actual magnitude,- — their true form, even to the inequalities on their surface, and (what seems much more out of his reach)