[50] It is said that Kepler saw this dark spot while looking at the sun in a camera obscura. As a camera obscura is actually a telescope, magnifying objects in proportion to the focal length of the lens employed, he may be said to have first seen these spots with the aid of an optical instrument.

Kepler was not one of those cold-hearted men who, though continually occupied in the study of the material world, and ambitious of the distinction which a successful examination of it confers, are yet insensible to the goodness and greatness of the Being who made and sustains it. His mind was cast in a better mould. The magnificence and harmony of the divine works excited in him not only admiration but love. He felt his own humility the farther he was allowed to penetrate into the mysteries of the universe; and sensible of the incompetency of his unaided powers for such transcendent researches, and recognising himself as but the instrument which the Almighty employed to make known his wonders, he never entered upon his inquiries without praying for assistance from above. This frame of mind was by no means inconsistent with that high spirit of delight and triumph with which Kepler surveyed his discoveries. His was the unpretending ovation of success, not the ostentatious triumph of ambition; and if a noble pride did occasionally mingle itself with his feelings, it was the pride of being the chosen messenger of physical truth, not that of being the favoured possessor of superior genius. With such a frame of mind, Kepler was necessarily a Christian. The afflictions with which he was beset confirmed his faith and brightened his hopes: he bore them in all their variety and severity with Christian patience; and though he knew that this world was to be the theatre of his intellectual glory, yet he felt that his rest and his reward could be found only in another.

It is difficult to form any very intelligible idea of the nature and extent of Kepler's astrological opinions, and of the degree of credit which he himself placed in the opinions that he did avow. In his Principles of Astrology, published in 1602, and in other works, he rails against the vanity and worthlessness of the ordinary astrology. He regards those who professed it as knaves and charlatans; and maintains that the planets and stars exercise no influence whatever over human affairs. He conceives, however, that certain harmonious configurations of suitable planets, like the spur to a horse, or a speech to an audience, have the power of exciting the minds of men to certain general actions or impulses; so that the only effect of these configurations is to operate along with the vital soul in producing results which would not otherwise have taken place. As an example of this, he states that those who are born when many aspects of the planets occur, generally turn out busy and industrious, whether they be occupied in amassing wealth, managing public affairs, or prosecuting scientific studies. Kepler himself was born under a triple configuration, and hence, in his opinion, his ardour and activity in study; and he informs us that he knew a lady born under nearly the same configurations, "who not only makes no progress in literature, but troubles her whole family and occasions deplorable misery to herself." This excitement of the faculties of sublunary natures, as he expresses it, by the colours and aspects and conjunctions of the planets, is regarded by Kepler as a fact, which he had deduced from observation, and which has "compelled his unwilling belief." "I have been driven to this," says he, "not by studying or admiring Plato, but singly and solely by observing seasons, and noting the aspects by which they are produced. I have seen the state of the atmosphere almost uniformly disturbed as often as the planets are in conjunction, or in the other configurations so celebrated among astrologers. I have noticed its tranquil state either when there are none or few such aspects, or when they are transitory and of short duration." Had Kepler been able to examine these hasty and erroneous deductions by long continued observation, he would soon have found that the coincidence which he did observe was merely accidental, and he would have cheerfully acknowledged it. Speculations of this kind, however, are, from their very nature, less subject to a rigorous scrutiny; and a long series of observations is necessary either to establish or to overturn them. The industry of modern observers has now supplied this defect, and there is no point in science more certain than that the sun, moon, and planets do not exercise any influence on the general state of our atmosphere.

The philosophers in Kepler's day, who had studied the phenomena of the tides, without having any idea of their cause, and who observed that they were clearly related to the daily motions of the two great luminaries, may be excused for the extravagance of their belief in supposing that the planets exercised other influences over "sublunary nature." Although Kepler, in his Commentaries on Mars, had considered it probable that the waters of our ocean are attracted by the moon, as iron is by a loadstone, yet this opinion seems to have been a very transient one, as he long afterwards, in his System of Harmonies, stated his firm belief that the earth is an enormous living animal, and enumerates even the analogies between its habits and those of known animated beings. He considered the tides as waves produced by the spouting out of water through its gills, and he explains their relation to the solar and lunar motions by supposing that the terrene monster has, like other animals, its daily and nightly alternations of sleeping and waking.

From the consideration of Kepler's astrological opinions, it is an agreeable transition to proceed to the examination of his high merits as an astronomer and a philosopher. As an experimental philosopher, or as an astronomical observer, Kepler does not lay claim to our admiration. He himself acknowledges, "that for observations his sight was dull, and for mechanical operations his hand was awkward." He suffered much from weak eyes, and the delicacy of his constitution did not permit him to expose himself to the night air. Notwithstanding these hindrances, however, he added several observations to those of Tycho, which he made with two instruments that were presented to him by his friend Hoffman, the President of the States of Styria. These instruments were an iron sextant, 2-1/2 feet in diameter, and a brass azimuthal quadrant 3-1/2 feet in diameter, both of which were divided into single minutes of a degree. They were very seldom used, and we must regard the circumstances which disqualified Kepler for an observer, as highly favourable to the developement of those great powers which he directed with undivided energy to physical astronomy.

Even if Kepler had never turned his attention to the heavens, his optical labours would have given him a high rank among the original inquirers of his age; but when we consider him also as the discoverer of the three great laws which bear his name, we must assign him a rank next to that of Newton. The history of science does not present us with any discoveries more truly original, or which required for their establishment a more powerful and vigorous mind. The speculations of his predecessors afforded him no assistance. From the cumbrous machinery adopted by Copernicus, Kepler passed, at one step, to an elliptical orbit, with the sun in one of its foci, and from that moment astronomy became a demonstrative science. The splendid discoveries of Newton sprung immediately from those of Kepler, and completed the great chain of truths which constitute the laws of the planetary system. The eccentricity and boldness of Kepler's powers form a striking contrast with the calm intellect and the enduring patience of Newton. The bright spark which the genius of the one elicited, was fostered by the sagacity of the other into a steady and a permanent flame.

Kepler has fortunately left behind him a full account of the methods by which he arrived at his great discoveries. What other philosophers have studiously concealed, Kepler has openly avowed, and minutely detailed; and we have no hesitation in considering these details as the most valuable present that has ever been given to science, and as deserving the careful study of all who seek to emulate his immortal achievements. It has been asserted that Newton made his discoveries by following a different method; but this is a mere assumption, as Newton has never favoured the world with any account of the erroneous speculations and the frequent failures which must have preceded his ultimate success. Had Kepler done the same, by recording only the final steps of his inquiries, his method of investigation would have obtained the highest celebrity, and would have been held up to future ages as a pattern for their imitation. But such was the candour of his mind, and such his inordinate love of truth, that he not only recorded his wildest fancies, but emblazoned even his greatest errors. If Newton had indulged us with the same insight into his physical inquiries, we should have witnessed the same processes which were employed by Kepler, modified only by the different characters and intensities of their imaginative powers.

When Kepler directed his mind to the discovery of a general principle, he set distinctly before him, and never once lost sight of, the explicit object of his search. His imagination, now unreined, indulged itself in the creation and invention of various hypotheses. The most plausible, or perhaps the most fascinating, of these was then submitted to a rigorous scrutiny; and the moment it was found to be incompatible with the results of observation and experiment, it was willingly abandoned, and another hypothesis submitted to the same severe ordeal. By thus gradually excluding erroneous views and assumptions, Kepler not only made a decided approximation to the object of his pursuit, but in the trials to which his opinions were submitted, and in the observations or experiments which they called forth, he discovered new facts and arrived at new views which directed his subsequent inquiries. By pursuing this method, he succeeded in his most difficult researches, and discovered those beautiful and profound laws which have been the admiration of succeeding ages. In tracing the route which he followed, it is easy for those who live under the light of modern science to say that his fancies were often wild, and his labour often wasted; but, in judging of Kepler's methods, we ought to place ourselves in his times, and invest ourselves with the opinions and the knowledge of his contemporaries.

In the infancy of a science there is no speculation so absurd as not to merit examination. The most remote and fanciful explanations of facts have often been found the true ones; and opinions which have in one century been objects of ridicule, have in the next been admitted among the elements of our knowledge. The physical world teems with wonders, and the various forms of matter exhibit to us properties and relations far more extraordinary than the wildest fancy could have conceived. Human reason stands appalled before this magnificent display of creative power, and they who have drunk deepest of its wisdom will be the least disposed to limit the excursions of physical speculation.

The influence of the imagination as an instrument of research, has, we think, been much overlooked by those who have ventured to give laws to philosophy. This faculty is of the greatest value in physical inquiries. If we use it as a guide, and confide in its indications, it will infallibly deceive us; but if we employ it as an auxiliary, it will afford us the most invaluable aid. Its operation is like that of the light troops which are sent out to ascertain the strength and position of an enemy. When the struggle commences, their services terminate; and it is by the solid phalanx of the judgment that the battle must be fought and won.

G. S. TULLIS, PRINTER, CUPAN.

Transcriber's Notes and Errata The following typographical errors have been corrected: Error Correction betwen between his his his secretry secretary there sidence the residence guaging gauging

THE END