Why they are? The first question is soon disposed of by declaring positively that he has examined the heavens with Galileo’s own glass, and that no such thing as a satellite about Jupiter exists. To the second, he declares solemnly that he does not more surely know, that he has a soul in his body than that reflected rays are the sole cause of Galileo’s erroneous observations. In regard to the third question, he says, that these planets are like the smallest fly compared to an elephant; and finally, concludes on the fourth, that the only use of them is to gratify Galileo’s ‘thirst of gold,’ and to afford himself a subject of discussion. Kepler, in a letter to Galileo, when alluding to Horky, says, ‘He begged so hard to be forgiven, that I have taken him again into favour upon this preliminary condition--that I am to show him Jupiter’s satellites, AND HE IS TO SEE THEM, and own that they are there.’ The following is a specimen of the reasoning of certain pretended philosophers of that age against the discoveries of Galileo. Sizzi, a Florentine astronomer, reasons in this strain: ‘There are seven windows given to animals in the domicile of the head, through which the air is admitted to the rest of the tabernacle of the body to enlighten, to warm and to nourish it; two nostrils, two eyes, two ears, and a mouth; so in the heavens, or the great world, there are two favourable stars, two unpropitious, two luminaries, and Mercury alone undecided and indifferent. From which and many other similar phenomena in nature, such as the seven metals, &c., we gather that the number of planets is _necessarily seven_. Moreover, the satellites are invisible to the naked eye, and therefore can exert no influence on the earth, and therefore would be useless, _and therefore do not exist_. Besides, as well the Jews as other ancient nations have adopted the division of the week into seven days, and have named them from the seven planets. Now, if we increase the number of the planets, this whole system falls to the ground.’ The opinions which then prevailed in regard to Galileo’s observations on the moon, were such as the following:--Some thought that the dark shades on the moon’s surface arose from the interposition of opaque bodies floating between her and the sun, which prevent his light from reaching those parts; others imagined that, on account of her vicinity to the earth, she was partly tainted with the imperfections of our terrestrial and elementary nature, and was not of that entirely pure and refined substance of which the more remote heavens consist: and a third party looked on her as a vast mirror, and maintained that the dark parts of her surface were the reflected images of our earthly forests and mountains.