the phenomena, by meeting with some which it did not enable him to explain. Milton, whose poem is filled with allusions to Galileo and his astronomy, has not suffered this beautiful phenomenon to pass unnoticed. After describing the creation of the Sun, he adds:— Hither, as to their fountain, other stars Repairing, in their golden urns draw light, And hence the morning planet gilds her horns.[60] Galileo also assured himself, at the same time, that the fixed stars did not receive their light from the sun. This he ascertained by comparing the vividness of their light, in all positions, with the feebleness of that of the distant planets, and by observing the different degrees of brightness with which all the planets shone at different distances from the sun. The more remote planets did not, of course, afford equal facilities with Venus for so decisive an observation; but Galileo thought he observed, that when Mars was in quadratures, (or in the quarters, the middle points of his path on either side,) his figure varied slightly from a perfect circle. Galileo concludes the letter, in which he announces these last observations to his pupil Castelli, with the following expressions, shewing how justly he estimated the opposition they encountered:—"You almost make me laugh by saying that these clear observations are sufficient to convince the most obstinate: it seems you have yet to learn that long ago the observations were enough to convince those who are capable of reasoning, and those who wish to learn the truth; but that to convince the obstinate, and those who care for nothing beyond the vain applause of the stupid and senseless vulgar, not even the testimony of the stars would suffice, were they to descend on earth to speak for themselves. Let us then endeavour to procure some knowledge for ourselves, and rest contented with this sole satisfaction; but of advancing in popular opinion, or gaining the assent of the book-philosophers, let us abandon both the hope and the desire." FOOTNOTES: [56] Adone di Marini, Venetiis, 1623, Cant. x. [57] Speculat. Lib Venetiis, 1585, Epistolæ. [58] This opinion, with respect to the milky way, had been held by some of the ancient astronomers. _See_ Manilius. Lib. i. v. 753. "_Anne magis densâ stellarum turba coronâ_ "_Contexit flammas, et crasso lumine candet,_ "_Et fulgore nitet collato clarior orbis._" [59] Huyghens announced his discovery in this form: _a a a a a a a c c c c c d e e e e e g h i i i i i i i l l l l m m n n n n n n n n n o o o o p p q r r s t t t t t u u u u u_, which he afterwards recomposed into the sentence. _Annulo cingitur, tenui, plano, nusquam cohærente, ad eclipticam inclinato_. De Saturni Lunâ. Hagæ, 1656. [60] B. vii. v. 364. Other passages may be examined in B. i. 286; iii. 565-590, 722-733; iv. 589; v. 261, 414; vii. 577; viii. 1-178. CHAPTER IX. _Account of the Academia Lincea—Del Cimento—Royal Society._