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Rh Finally, the "Conclusion" of the volume (pp. 787–816) gives first a rapid summary of the contents of the book, and then deals with two questions not yet touched upon, the physical nature of the new star and the astrological effect and signification, which the author did not wish to enter on in the body of the work, "as these matters are not subject to the senses, nor to any geometrical demonstration, but can only be speculated on." As to the nature of the star, Tycho considers that it 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. This idea may to the modern reader seem absurd, but it should be remembered that the telescope had not yet revealed the true nature of the Milky Way, and Tycho's ideas about the latter were at all events a great advance from those of Aristotle (which he sharply attacks), according to which the Milky Way was merely an atmospheric agglomeration of stellar matter. With regard to the other question, the astrological signification of the star, Tycho had evidently considered it a good deal since he wrote his little book in 1573, and he does not on this occasion merely express himself in very general terms, but gives his opinion with more decision. As his prediction attracted a good deal of attention, particularly later when it seemed to have been fulfilled, it is worth while to give a short summary of it.

As the star of Hipparchus announced the extinction of the Greek ascendency and the rise of the Roman empire,