Galileo Advocates Copernicus’ Theory

Kepler urged him to publish his arguments in favor of the Copernican theory, but he hesitated for the present, knowing that his declaration would be received with ridicule and opposition.

Continuing Galileo’s Discoveries,
our selection from Pioneers of Science by Sir Oliver Lodge published in 1893. For works benefiting from the latest research see the “More information” section at the bottom of these pages. The selection is presented in six easy 5 minute installments.

Previously in Galileo’s Discoveries.

Time: 1586-1638
Place: Padua, Italy

Yet they had received a shock: as by a breath of fresh salt breeze and a dash of spray in their faces, they had been awakened out of their comfortable lethargy. They felt the approach of a new era. Yes, it was a shock, and they hated the young Galileo for giving it them — hated him with the sullen hatred of men who fight for a lost and dying cause.

We need scarcely blame these men; at least we need not blame them overmuch. To say that they acted as they did is to say that they were human, were narrow-minded, and were the apostles of a lost cause. But they could not know this; they had no experience of the past to guide them; the conditions under which they found themselves were novel, and had to be met for the first time. Conduct which was excusable then would be unpardonable now, in the light of all this experience to guide us. Are there any now who practically repeat their error, and resist new truth? who cling to any old anchorage of dogma, and refuse to rise with the tide of advancing knowledge? There may be some even now.

Well, the unpopularity of Galileo smouldered for a time, until, by another noble imprudence, he managed to offend a semiroyal personage, Giovanni de’ Medici, by giving his real opinion, when consulted, about a machine which De’ Medici had invented for cleaning out the harbor of Leghorn. He said it was as useless as it in fact turned out to be. Through the influence of the mortified inventor he lost favor at court; and his enemies took advantage of the fact to render his chair untenable. He resigned before his three years were up, and retired to Florence.

His father at this time died, and the family were left in narrow circumstances. He had a brother and three sisters to provide for. He was offered a professorship at Padua for six years by the Senate of Venice, and willingly accepted it. Now began a very successful career. His introductory address was marked by brilliant eloquence, and his lectures soon acquired fame. He wrote for his pupils on the laws of motion, on fortifications, on sun-dials, on mechanics, and on the celestial globe: some of these papers are now lost, others have been printed during the present century.

Kepler sent him a copy of his new book, Mysterium Cosmographicum, and Galileo, in thanking him for it, writes him the following letter:

I count myself happy, in the search after truth, to have so great an ally as yourself, and one who is so great a friend of the truth itself. It is really pitiful that there are so few who seek truth, and who do not pursue a perverse method of philosophizing. But this is not the place to mourn over the miseries of our times, but to congratulate you on your splendid discoveries in confirmation of truth. I shall read your book to the end, sure of finding much that is excellent in it. I shall do so with the more pleasure, because I have been for many years an adherent of the Copernican system, and it explains to me the causes of many of the appearances of nature which are quite unintelligible on the commonly accepted hypothesis. I have collected many arguments for the purpose of refuting the latter; but I do not venture to bring them to the light of publicity, for fear of sharing the fate of our master, Copernicus, who, although he has earned immortal fame with some, yet with very many (so great is the number of fools) has become an object of ridicule and scorn. I should certainly venture to publish my speculations if there were more people like you. But this not being the case, I refrain from such an undertaking.”

Kepler urged him to publish his arguments in favor of the Copernican theory, but he hesitated for the present, knowing that his declaration would be received with ridicule and opposition, and thinking it wiser to get rather more firmly seated in his chair before encountering the storm of controversy. The six years passed away, and the Venetian Senate, anxious not to lose so bright an ornament, renewed his appointment for another six years at a largely increased salary.

Soon after this appeared a new star — the stella nova of 1604 — not the one Tycho had seen — that was in 1572 — but the same that Kepler was so much interested in. Galileo gave a course of three lectures upon it to a great audience. At the first the theatre was overcrowded, so he had to adjourn to a hall holding one thousand persons. At the next he had to lecture in the open air. He took occasion to rebuke his hearers for thronging to hear about an ephemeral novelty, while for the much more wonderful and important truths about the permanent stars and facts of nature they had but deaf ears.

But the main point he brought out concerning the new star was that it upset the received Aristotelian doctrine of the immutability of the heavens. According to that doctrine the heavens were unchangeable, perfect, subject neither to growth nor to decay. Here was a body, not a meteor but a real distant star, which had not been visible and which would shortly fade away again, but which meanwhile was brighter than Jupiter.

The staff of petrified professorial wisdom were annoyed at the appearance of the star, still more at Galileo’s calling public attention to it; and controversy began at Padua. However, he accepted it, and now boldly threw down the gauntlet in favor of the Copernican theory, utterly repudiating the old Ptolemaic system, which up to that time he had taught in the schools according to established custom.

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