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CHAPTER IV.

ASTRONOMY AND THEOLOGY.

Treatise on Floating Bodies.—Controversy with Scheiner about the Solar Spots.—Favourable reception of Galileo's work on the subject at Rome.—Discussion with the Grand Duchess Christine.—The Bible brought into the controversy.—Ill-fated Letter to Castelli.—Caccini's Sermon against Galileo.—Lorini denounces the Letter to the Holy Office.— Archbishop Bonciani's attempts to get the original Letter.—"Opinion" of the Inquisition on it.—Caccini summoned to give evidence.—Absurd accusations.—Testimony of Ximenes and Attavanti in Galileo's favour.

 

While the storm which was to burst over Galileo's head was thus slowly gathering, he was making important progress in the departments of physics and mechanics.

His treatise on the motion of floating bodies led to very important results.^[1] In it he again took the field against the Peripatetic philosophers, and refuted the assertion of Aristotle that the floating or partial immersion of bodies in water depended chiefly on their form, for by his approved method of studying the open book of nature he clearly showed the error of that opinion. In this work Galileo laid the foundations of hydrostatics as mostly held to this day. The old school rose up once more to refute him, as a matter of course; but their polemics cut a pitiful figure, for the champions of antiquated wisdom had in their impotence mostly to content themselves with wretched sophisms as opposed to Galileo's hard facts, and as a last resort to insist on the authority of Aristotle.

The combatants who took the field with various writings to

1. "Discorso al Serenissimo D. Cosimo II., Gran-Duca di Toscana intorno alle cose che stanno in su l'aqua o che in quella si muovano."