[1610-1632 A.D.]
During the pontificate of Urban VIII, an interesting controversy between science and theology reached a culmination in the persecution of Italy’s most famous scientist of the century, Galileo. This great experimental philosopher had developed the telescope, and in 1610 made the discovery of the satellites of Jupiter. This discovery, along with others almost equally interesting, was announced in Galileo’s Nuncius Sidereus, published at Venice in 1610.[a]
The title of this work will best convey an idea of the claim it made to public notice: “The Sidereal Messenger, announcing great and very wonderful spectacles, and offering them to the consideration of everyone, but especially of philosophers and astronomers; which have been observed by Galileo Galilei, etc., by the assistance of a perspective glass lately invented by him; namely, in the face of the moon, in innumerable fixed stars in the milky-way, in nebulous stars, but especially in four planets which revolve round Jupiter at different intervals and periods with a wonderful celerity; which, hitherto not known to any one, the author has recently been the first to detect, and has decreed to call the Medicean stars.”
The interest this discovery excited was intense; and men were at this period so little habituated to accommodate their convictions on matters of science to newly observed facts that several of “the paper-philosophers,” as Galileo termed them, appear to have thought they could get rid of these new objects by writing books against them. The effect which the discovery had upon the reception of the Copernican system was immediately very considerable. It showed that the real universe was very different from that which ancient philosophers had imagined, and suggested at once the thought that it contained mechanism more various and more vast than had yet been conjectured. And when the system of the planet Jupiter thus offered to the bodily eye a model or image of the solar system according to the views of Copernicus, it supported the belief of such an arrangement of the planets, by an analogy all but irresistible.
Galileo Galilei
Later in the same year Galileo observed and reported the phases of the planet Venus, thus further corroborating the Copernican doctrine. This doctrine when first promulgated by Copernicus had apparently excited no very great alarm among the theologians of the time. But its assertion and confirmation by Galileo now provoked a storm of controversy, and was visited by severe condemnation. Galileo’s own behaviour appears to have provoked the interference of the ecclesiastical authorities; but there must have been a great change in the temper of the times to make it possible for his adversaries to bring down the sentence of the Inquisition upon opinions which had been so long current without giving any serious offence.
The heliocentric doctrine had for a century been making its way into the minds of thoughtful men, on the general ground of its simplicity and symmetry. Galileo appears to have thought that now, when these original recommendations of the system had been reinforced by his own discoveries and reasonings, it ought to be universally acknowledged as a truth and a reality. And when arguments against the fixity of the sun and the motion of the earth were adduced from the expressions of Scripture, he could not be satisfied without maintaining his favourite opinion to be conformable to Scripture as well as to philosophy; and he was very eager in his attempts to obtain from authority a declaration to this effect. The ecclesiastical authorities were naturally averse to express themselves in favour of a novel opinion, startling to the common mind, and contrary to the most obvious meaning of the words of the Bible; and when they were compelled to pronounce, they decided against Galileo and his doctrines. He was accused before the Inquisition in 1615; but at that period the result was that he was merely recommended to confine himself to the mathematical reasonings upon the system, and to abstain from meddling with the Scripture. Galileo’s zeal for his opinions soon led him again to bring the question under the notice of the pope, and the result was a declaration of the Inquisition that the doctrine of the earth’s motion appeared to be contrary to the sacred Scripture. Galileo was prohibited from defending and teaching this doctrine in any manner, and promised obedience to this injunction. But in 1632 he published his Dialogo delli due Massimi Sistemi del Mondo, Tolemaico e Copernicano;[g] and in this, he defended the heliocentric system by all the strongest arguments which its admirers used. Not only so, but he introduced into this Dialogue a character under the name of Simplicius, in whose mouth was put the defence of all the ancient dogmas, and who was represented as defeated at all points in the discussion; and he prefixed to the Dialogue a notice, To the Discreet Reader, in which, in a vein of transparent irony, he assigned his reasons for the publication. “Some years ago,” he says, “a wholesome edict was promulgated at Rome, which, in order to check the perilous scandals of the present age, imposed silence upon the Pythagorean opinion of the motion of the earth. There were not wanting,” he adds, “persons who rashly asserted that this decree was the result, not of a judicious inquiry, but of a passion ill-informed; and complaints were heard that counsellors, utterly unacquainted with astronomical observations, ought not to be allowed, with their undue prohibitions, to clip the wings of speculative intellects. At the hearing of rash lamentations like these, my zeal could not keep silence.” And he then goes on to say that he wishes, by the publication of his Dialogue, to show that the subject had been fully examined at Rome. The result of this was that Galileo was condemned for his infraction of the injunction laid upon him in 1616; his Dialogue was prohibited; he himself was commanded to abjure on his knees the doctrine which he had taught; and this abjuration he performed.
The ecclesiastical authorities having once declared the doctrine of the earth’s motion to be contrary to Scripture and heretical, long adhered in form to this declaration, and did not allow the Copernican system to be taught in any other way than as an “hypothesis.”[f]