DISCOVEEIES IN THE CELESTIAL SPACES. 709 



like all that refers to physical astronomy, more general atten- 

 tion, from the fact that several great discoveries in the heavens 

 had aroused the attention of the public mass at the respective 

 periods of thirty-six, eight, and four years prior to the inven- 

 tion of the telescope in 1608, viz., the sudden apparition and 

 disappearance of three new stars, one in Cassiopea in 1572, 

 another in the constellation of the Swan in 1600, and the 

 third in the foot of Ophiuchus in 1604. All these stars were 

 brighter than those of the first magnitude, and the one 

 observed by Kepler in the Swan continued to shine in the 

 heavens for twenty-one years, throughout the whole period of 

 Galileo's discoveries. Three centuries and a half have now 

 nearly passed since then, but no new star of the first or 

 second magnitude has appeared; for the remarkable event 

 witnessed by Sir John Herschel in the southern hemisphere 

 (in 1837),* was a great increase in the intensity of the light 

 of a long known star of the second magnitude (77 Argo), 

 which had not until then been recognised as variable. The 

 writings of Kepler and our own experience of the effect pro- 

 duced by the appearance of comets visible to the naked eye, 

 will teach us to understand how powerfully the appearance of 

 new stars, between the years 1572 and 1604, must have 

 arrested attention, increased the general interest in astrono- 

 mical discoveries, and excited the minds of men to the com- 

 bination of imaginative conjectures. Thus, too, terrestrial 

 natural events, as earthquakes in regions where they have 

 been but seldom experienced; the eruption of volcanoes that 

 had long remained inactive ; the sounds of aerolites traversing 

 our atmosphere and becoming ignited within its confines, 

 impart a new stimulus, for a certain time, to the general 

 interest in problems, which appear to the people at large 

 even more mysterious than to the dogmatising physicist. 



My reason for more particularly naming Kepler in these 

 remarks on the influence of direct sensuous contemplation, 

 has been to point out how, in this great and highly-gifted 

 man, a taste for imaginative combinations was combined with 

 a remarkable talent for observation, an earnest and severe 

 method of induction, a courageous and almost unparalleled 

 perseverance in calculation, and a mathematical profoundness 

 of mind, which revealed, in his Stereometria doliorum, exer- 



* Compare Cosmos., pp. 54, and 363. 



