'When we consider merely the vast dimensions of the celestial sphere in comparison with the littleness of our earth . . . and then think of the speed of the motion by which a whole revolution of the heavens must be accomplished in one day, I cannot persuade myself that the heavens turn while the earth stands fast.'

Adducing not merely the sun spots themselves, but their rapid variation, he insists that the universe is not rigid and permanent, but constantly changing or, as science has more and more emphasized since his day, passing through consecutive, related phases or evolving.

'I can listen only with the greatest repugnance when the quality of unchangeability is held up as something preëminent and complete in contrast to variability. I hold the earth for most distinguished exactly on account of the transformations which take place upon it.'

He begins to see the fallacy of the objections that if the earth rotated, a body dropped from a masthead would be left behind by the ship and that movable objects could be thrown off centrifugally at the equator. As positive arguments in support of the Copernican system, he urges particularly the retrogressions and other irregularities of the planets, and also the tides.

Of the famous controversy of Galileo with the Inquisition, it may here suffice to quote the judgment of the court (see Appendix):

"The proposition that the sun is in the centre of the world and immovable from its place is absurd, philosophically false and formally heretical; because it is expressly contrary to the Holy Scriptures,' etc. and a passage from the biographer already cited at so much length :

For over fifty years he was the knight militant of science, and almost alone did successful battle with the hosts of Churchmen and Aristotelians who attacked him on all sides one man against a world of bigotry and ignorance. If then, . . . once, and only once, when face to face with the terrors of the Inquisition, he, like Peter, denied his Master, no honest man, knowing all the circumstances, will be in a hurry to blame him.

Q

Of Galileo's still more remarkable services to physics and dynamics, something will be added in a later chapter.

MEDICAL AND CHEMICAL SCIENCES. - These were still at the low medieval level. There was as yet no scientific medicine, and no chemistry but alchemy, which was now in its final stage, iatro (medical) chemistry. Here one great name is that of Paracelsus (1493-1541), erratic and radical Swiss physician and alchemist, whose chief merit is his courage in opposing mere authority in science, and whose influence long after caused "salt, sulphur, and mercury" to be highly regarded and carefully studied. He also introduced and insisted upon the importance of antimony as a remedy, and is said to have been the first to use that tincture of opium which is still known by his name for it; viz. laudanum. Paracelsus, on the other hand, in spite of the fact that he was a popular surgeon, rejected the study of anatomy, taught medical knowledge through scanning of the heavens, and considered diseases as spiritual in origin. "The true use of chemistry," he said, "is not to make gold but to prepare medicines."

Another name worthy of remembrance in the chemistry of the sixteenth century is that of Landmann (Latin, Agricola) whose great work on Metallurgy (De Re Metallica, 1546) is the most important of this period, and who must also be regarded as the first mineralogist of modern times.

ANATOMY. VESALIUS.-Hardly less important, meantime, than the studies of Copernicus, Tycho Brahe, Galileo and Kepler upon the heavenly bodies were those of the Belgian anatomist, Andreas Vesalius, upon the human body. For more than 1000 years there had been almost no progress in anatomy or medicine, Hippocrates and Galen being still regarded as the final authorities in these matters up to the middle of the sixteenth century. Vesalius (1514-1564), born in Brussels and educated in Paris, was the first in modern times to dissect the human body, and to publish excellent drawings of his dissections. It was said that he opened the body of a nobleman before the heart had entirely ceased beating, and thereby incurring the displeasure of the Inquisition, was sen

tenced to perform a penitential journey to Jerusalem. At all events, he went to Jerusalem and was shipwrecked and lost while returning.

After Vesalius the study of human anatomy was vigorously and successfully prosecuted in Italy as was natural, since it was in Italy that Humanism and the revival of learning first took firm hold of Christian Europe. One of Vesalius' Italian contemporaries, Eustachius, whose name is still familiarly associated with the passage or "tube" connecting the throat and the middle ear, is hardly less famous in the history of anatomy than is Vesalius himself. The name of Fallopius, professor at Pisa in 1548 and at Padua in 1551, is also similarly associated with the human oviducts, -the so-called Fallopian tubes. His disciple Fabricius of Acquapendente discovered the valves in the veins, and was the teacher of William Harvey. A Spanish anatomist of note, Michael Servetus, -born 1509,- perished as a martyr at the stake in 1553 because of heretical writings abhorrent alike to the Inquisition and to Calvin.

Of physiology we have as yet little or no account. Doubtless all the anatomists just mentioned and many other "philosophers" had pondered, as did Aristotle and his predecessors, on the workings of the animal, and especially the human, mechanism. But from Aristotle (B.C. 322) to William Harvey (1578-1657) no real progress was made. It is a melancholy commentary on superstition and human prejudice that long after the brilliant work of Vesalius and the Italian anatomists, no proper "anatomy acts" existed to make lawful dissection either possible or easy, so that for several centuries afterward anatomists, surgeons, and medical students felt themselves at times obliged to resort to "body-snatching."

NATURAL HISTORY AND NATURAL PHILOSOPHY.- No great progress was made in this field after the observations of Aristotle, Theophrastus, Xenophanes, and Pythagoras until the sixteenth century. Fossils mostly remained unexplained or were regarded as "freaks" of nature. Animals and plants were comparatively neglected and, if studied, considered either as the raw material for supposed remedies or medicines, or else as treated by Aristotle. The