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General Considerations On Astronomy

( Originally Published 1913 )

THE history of man's knowledge, the gradual growth of his conceptions on the subject of the stars, would be the history of the human mind. In Astronomy, from its very simplicity, we see with greater distinctness the procession of human thought, from the time when the course of the stars seemed prophetic of man's destiny, and their wayward ever varying configurations seemed to drag with them the strange vicissitudes of life, to the time when positive science ascertained the main laws of the heavenly mechanism. In it may be seen amusingly illustrated the theological tendency of interpreting all phenomena according to human analogies, the metaphysical tendency of arguing instead of observing of substituting some logical deduction for the plain observation of a fact ; and finally, the positive tendency of limiting inquiry to accessible relations, and rejecting as idle all speculation which transcends our means.

Comte has not only devoted some four hundred pages of his second volume to an exposition of the main points necessary to be understood in a philosophic survey of Astronomy, but has also devoted a separate work to the subject (Treatise of Popular Astronomy), justly considering this science as one eminently calculated to render familiar his views of positive Method. In the remarks which are now to follow, Comte himself must be understood as speaking ; the sentences are translations, or analyses of what may be found in his work :And first, as to the possible extent of our sidereal knowledge.

Sight is the only one of our senses through which we can acquire a knowledge of celestial objects. Hence, the only qualities which can become known to us are their forms, their distances, their magnitudes, and their movements ; and Astronomy, therefore, may properly be defined thus :

It has for its object the discovery of the laws of the geometrical and mechanical phenomena presented to us by the heavenly bodies.

It is, however, necessary to add, that, in reality, the phenomena of all the heavenly bodies are not within the reach of scientific investigation.

Those philosophical minds who are strangers to the profound study of Astronomy, and even astronomers themselves, have not yet sufficiently distinguished, in the ensemble of our celestial investigations, between the solar point of view, as I may call it, and that which truly deserves the name of universal. This distinction, however, appears to me indispensable to mark precisely the line of separation between that part of the science which may be brought to a state completely perfect, and that which, without indeed being purely conjectural, must always remain in the stage of infancy, at least when contrasted with the first. The solar system, of which we form a part, evidently offers a subject of study whose boundaries are well marked ; it is susceptible of a thorough examination, and capable of leading us to the most satisfactory conclusions. But the idea of what we call the universe is, on the contrary, necessarily indefinite, so that, however extensive we would suppose our well grounded knowledge of this kind to become in the course of time, we should never be able to arrive at the true conception of the universe of stars. The difference is, at this moment, very striking indeed; for, with a solar astronomy in the high degree of perfection acquired during the last two centuries, we do not even yet possess, in sidereal astronomy, the first and simplest element of positive inquiry, the determination of the distances of the stars. Doubtless, we have reason for presuming (as I shall afterwards explain) that those distances will be determined, at least within certain limits, in the case of several stars ; and that, consequently, we shall know divers other important elements, which theory is quite prepared to deduce from this fundamental given quantity, such as their masses, &c. But the important distinction made above will by no means be affected thereby.

In every branch of our researches, and in all their chief aspects, there exists a constant and necessary harmony between the extent of our intellectual wants, and the real compass, present or future, of our knowledge. This harmony is neither the result nor the sign of a final cause, as our common place philosophers try to believe. It simply arises from this evident necessity : on the one hand we have only need of knowing what can act upon and affect us, more or less directly ; and on the other, it follows, from the very fact of there being such influencing agencies in operation, that we are thereby sooner or later supplied with a sure means of knowledge. This relation is made manifest in a remarkable manner in the case before us. The most complete study possible of the laws of the solar system of which we form a part, is of high interest to us, and we have succeeded in giving it an admirable precision. On the contrary, if an exact idea of the universe is necessarily interdicted to us, it is plain that this is of no real importance, except to our insatiable curiosity. The daily application of astronomy shows that the phenomena occurring within each solar system, being those which can alone affect its inhabitants, are essentially independent of the more general phenomena connected with the mutual action of the suns, almost like our meteorological phenomena in their relation to the planetary phenomena. Our tables of celestial events, prepared long beforehand, on the principle of taking no account of any other world in the universe save our own, have hitherto rigorously tallied with direct observations, however minute the precision we introduce into them. This independence, so palpable, is completely explained by the immense disproportion which we are certain exists between the mutual distances of the suns, and the small intervals between our planets. If, as is highly probable, the planets provided with atmospheres, as Mercury, Venus, Jupiter, &c., are really inhabited, we may regard their inhabitants as in some shape our fellow-citizens, seeing that from this sort of common country there would necessarily result a certain community of thoughts, and even of interests, while the inhabitants of the other solar systems must be entire aliens to us. It is therefore necessary to separate more profoundly than has hitherto been customary, the solar from the universal point of view, the idea of the world from that of the universe ; the first is the highest which we have been able actually to reach, and is, besides, the only one in which we are truly interested.

Hence, without renouncing all hope of obtaining some knowledge of the stars, it is necessary to conceive positive astronomy as consisting essentially in. the geometrical and mechanical study of the small number of heavenly bodies which compose the world of which we form a part. It is only within these limits that astronomy, from its perfection, merits the superior rank which it now holds among the sciences.

And here Comte calls attention to a very important philosophical law, never distinctly recognised before his It would be wrong to allow this passage to pass without qualification; all considerations, astronomical and zoological, lead us to the conclusion that these planets are inhabited by beings totally unlike the inhabitants of our own.

Enunciation of it viz.: That in proportion as the phenomena to be studied become more complex, they are, from their nature, susceptible of more extended and more varied means of exploration.

In other words, the complexity of the phenomena implies a greater variety of sources through which they can be investigated. If man had a sense the less, the phenomena now perceived by that sense would be wanting to him ; if he had a sense the more, he would perceive more phenomena. There is not, however, an exact compensation between the increase of difficulty and the increase of our resources, so that, notwithstanding this harmony, the sciences which refer to the most complex phenomena continue no less necessarily the most imperfect, in accordance with the encyclopædical scale established at the commencement of Comte's work. Astronomical phenomena, then, being the simplest, ought to be those for which the means of exploration are the most limited.

Our art of observing is, in general, composed of three different processes :

1st. Observation, properly so called that is to say, the direct examination of the phenomenon, as it naturally presents itself.

2nd. Experiment that is to say, the contemplation of the phenomena, more or less modified by circumstances artificially created by us, for the express purpose of a more perfect exploration.

3rd. Comparison that is to say, the gradual consideration of a series of analogous cases in which the phenomena become more and more simplified.

The science of organised bodies, which embraces the phenomena the most difficult of access, is at the same time the only one that truly permits the union of the three modes. Astronomy, on the contrary, is necessarily limited to the first. And observation is there restricted to that of a single sense. All that it does and it is all that is ' required is to measure angles, and reckon times elapsed. Observation, however indispensable, plays the most insignificant part in astronomy : it is Reasoning which forms incomparably the greatest portion of astronomical science, and this constitutes the prime basis of its intellectual dignity, It is our intelligence which constructs the greater number of astronomical phenomena, actual phenomena though they are. We neither, for example, see the figure of the earth nor the curve described by a planet.

The combination of these two essential characteristics —extreme simplicity of the phenomena, with great difficulty in their observation—is what makes astronomy a science so eminently mathematical. On the one hand, the constant necessity we are under of deducing from a small number of direct measures, both angular and horary quantities, which are not themselves immediately observable, renders the continual use of abstract mathematics absolutely indispensable. On the other hand, astronomical questions being always problems of geometry or problems of mechanics, naturally fall within the province of concrete mathematics. And finally, not only as respects the geometrical problems do we have perfect regularity of astronomical figures, but, as respects the mechanical, we have admirable simplicity of movements taking place in a medium whose resistance has hitherto been left out of account without error, and under the influence of a small number of forces constantly subject to one very simple law and these circumstances allow the application of the methods and the theories of Mathematics to a much greater extent than in any other case. There is perhaps not a single analytical process, a single geometrical or mechanical doctrine, which is not ultimately made use of in astronomical investigations, and the greater part of them have hitherto served no other primary purpose. Hence it is preeminently by a proper study of this application of them that we can acquire a just sentiment of the importance and the reality of mathematical speculations.

Reflecting on the singularly simple nature of astronomical researches, and the consequent facility of applying the whole of our mathematical resources to them in the most extensive way, we understand why astronomy is now placed at the head of the natural sciences. It merits this supremacy 1st. By the perfection of its scientific character ; 2nd. By the preponderating importance of the laws which it discloses to us.

After referring to several examples of the high practical utility of astronomy, Comte takes this science as an illustration of the fact, that the sublimest scientific speculations often, without premeditation, lead to the most ordinary practical and useful purposes, and he exposes the folly of those who would interdict all speculations except those which have obviously an immediate practical object in view.

On a closer examination of the present condition of the different fundamental sciences, we shall find that astronomy is the only one which is really and finally purged of all theological or metaphysical considerations. As respects Method, this is the first title it has to supremacy. It is there philosophical minds can effectually study in what a true Science really consists; and it is after this model that we ought to strive, as far as possible, to construct all the other fundamental sciences, having at the same time due regard to the differences, more or less profound, which necessarily result from the increasing complication of the phenomena.

Those who conceive Science as consisting of a simple accumulation of observed facts, have only to consider astronomy with some attention to feel how narrow and superficial is their notion. In it the facts are so simple, and of so little interest, that one cannot possibly fail to observe that only the connexion of them and the exact knowledge of their laws, constitute the science. What, in reality, is an astronomical fact ? Nothing else, or di narily, than this : a star has been seen at a particular instant, and under a correctly measured angle ; a circumstance, doubtless, of little importance in itself. The continual combination of these observations, and the more or less profound mathematical elaboration of them, characterize the science even in its most imperfect state. In reality, astronomy did not take its rise when the priests of Egypt or Chaldea had, with more or less exactness, made a series of empirical observations on the heavens, but only when the first Greek philosophers began to connect the general phenomenon of the diurnal movement with certain geometrical laws. The true and definite object of astronomical investigations always being to predict with certainty the actual state of the heavens at a future period, more or less distant, the establishment of the laws of the phenomena evidently affords the only means of arriving at this result ; the accumulation of observations cannot, of itself, be of any practical utility except as furnishing a solid foundation to our speculations. In one word, a true astronomy did not exist so long as mankind knew not, for example, how to foresee, with a certain degree of precision, by the aid at least of graphical process, and in particular by certain trigonometrical calculations, the instant of the rising of the sun, or of a star, on a given day and at a given place. This essential characteristic of the science has always been the same since its origin. All the steps in its subsequent progress have only consisted in giving to these predictions a greater and greater certainty and precision, by borrowing from direct observation the least possible number of given terms for the purpose of foreseeing the most distant future. No part of philosophy can manifest with greater force the truth of this fundamental axiom : every science has prevision for its object; which distinguishes real science from simple erudition, limited to the narrative of past events without any view to a future.

Not only is the true characteristic of a science more decidedly marked in astronomy than in any other branch of positive knowledge, but we may even say, that since the development of the theory of gravitation, it has attained the highest degree of philosophical perfection that any science can ever pretend to, as respects Method, the exact reduction of all phenomena, both in kind and in degree, to one general law, provided always that we confine the remark to solar astronomy. The gradual complication of phenomena may lead us to conceive a similar perfection as absolutely chimerical in the other fundamental sciences. But it is the general type which all men of science ought constantly to have in view, as being the one to which they must approximate as far as the corresponding phenomena will allow. It is in astronomy that we perceive in all its purity what the. positive explanation of a phenomenon is, without any inquiry as to the first or final cause of it ; and, finally, it is there we must learn the true character, and the essential conditions, of truly scientific hypotheses, no other science having employed this powerful instrument so extensively, and at the same time so fittingly.

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