;A NEW ASTRONOMY 205 



the latter, appeared now to have reached its limit, and many people 

 thought that the tide had already commenced to turn. 



Tycho considered that the new star was formed of * celestial 

 matter/ not differing from that of which the other stars are composed, 

 except that it was not of such perfection or solid composition as in 

 the stars of permanent duration. It was therefore gradually dissolved 

 and dwindled away. It became visible to us because it was illuminated 

 by the sun, and the matter of which it was formed was taken from the 

 Milky Way, close to the edge of which the star was situated, and in 

 which Tycho believed he could now see a gap or hole which had not 

 been there before. 



But the star had a truer mission than that of announcing the 

 arrival of an impossible golden age. It roused to unwearied exertions 

 a great astronomer, it caused him to renew astronomy in all its branches 

 by showing the world how little it knew about the heavens; his 

 work became the foundation on which Kepler and Newton built their 

 glorious edifice, and the star of Cassiopeia started astronomical science 

 on the brilliant career which it has pursued ever since, and swept 

 away the mist that obscured the true system of the world. As Kepler 

 truly said, 'If that star did nothing else, at least it announced and 

 produced a great astronomer.' 



At the same time the book bears witness to the soberness of mind 

 which distinguishes him from most of the other writers on the subject 

 of the star. His account of it is very short, but it says all there 

 could be said about it that it had no parallax, that it remained 

 immovable in the same place, that it looked like an ordinary star 

 and it describes the star's place in the heavens accurately, and its 

 variations in light and color. Even though Tycho made some re- 

 marks about the astrological significance of the star, he did so in a 

 way which shows that he did not himself consider this the most valu- 

 able portion of his work. To appreciate his little book perfectly, it 

 is desirable to glance at some of the other numerous books and pam- 

 phlets which were written about the star, and of most of which 

 Tycho himself has in his later work given a very detailed analysis. 



In 1575 Tycho obtained while travelling a copy of Copernicus' 

 Commentariolus, and in the following year received from King 

 Frederick II the island of Hveen, with funds for the maintenance 

 of an observatory upon it. As to the former his opinion is that 



