History of the Conflict Between Religion and Science

by John William Draper

DA VINCI. The science of the Arabians followed the invading track of their literature, which had come into Christendom by two routes—the south of France, and Sicily. Favored by the exile of the popes to Avignon, and by the Great Schism, it made good its foothold in Upper Italy. The Aristotelian or Inductive philosophy, clad in the Saracenic costume that Averroes had given it, made many secret and not a few open friends. It found many minds eager to receive and able to appreciate it. Among these were Leonardo da Vinci, who proclaimed the fundamental principle that experiment and observation are the only reliable foundations of reasoning in science, that experiment is the only trustworthy interpreter of Nature, and is essential to the ascertainment of laws. He showed that the action of two perpendicular forces upon a point is the same as that denoted by the diagonal of a rectangle, of which they represent the sides. From this the passage to the proposition of oblique forces was very easy. This proposition was rediscovered by Stevinus, a century later, and applied by him to the explanation of the mechanical powers. Da Vinci gave a clear exposition of the theory of forces applied obliquely on a lever, discovered the laws of friction subsequently demonstrated by Amontons, and understood the principle of virtual velocities. He treated of the conditions of descent of bodies along inclined planes and circular arcs, invented the camera-obscura, discussed correctly several physiological problems, and foreshadowed some of the great conclusions of modern geology, such as the nature of fossil remains, and the elevation of continents. He explained the earth-light reflected by the moon. With surprising versatility of genius he excelled as a sculptor, architect, engineer; was thoroughly versed in the astronomy, anatomy, and chemistry of his times. In painting, he was the rival of Michel Angelo; in a competition between them, he was considered to have established his superiority. His "Last Supper," on the wall of the refectory of the Dominican convent of Sta. Maria delle Grazie, is well known, from the numerous engravings and copies that have been made of it.

ITALIAN SCIENTIFIC SOCIETIES. Once firmly established in the north of Italy, Science soon extended her sway over the entire peninsula. The increasing number of her devotees is indicated by the rise and rapid multiplication of learned societies. These were reproductions of the Moorish ones that had formerly existed in Granada and Cordova. As if to mark by a monument the track through which civilizing influences had come, the Academy of Toulouse, founded in 1345, has survived to our own times. It represented, however, the gay literature of the south of France, and was known under the fanciful title of "the Academy of Floral Games." The first society for the promotion of physical science, the Academia Secretorum Naturae, was founded at Naples, by Baptista Porta. It was, as Tiraboschi relates, dissolved by the ecclesiastical authorities. The Lyncean was founded by Prince Frederic Cesi at Rome; its device plainly indicated its intention: a lynx, with its eyes turned upward toward heaven, tearing a triple-headed Cerberus with its claws. The Accademia del Cimento, established at Florence, 1657, held its meetings in the ducal palace. It lasted ten years, and was then suppressed at the instance of the papal government; as an equivalent, the brother of the grand-duke was made a cardinal. It numbered many great men, such as Torricelli and Castelli, among its members. The condition of admission into it was an abjuration of all faith, and a resolution to inquire into the truth. These societies extricated the cultivators of science from the isolation in which they had hitherto lived, and, by promoting their intercommunication and union, imparted activity and strength to them all.

Returning now from this digression, this historical sketch of the circumstances under which science was introduced into Europe, I pass to the consideration of its manner of action and its results.

INTELLECTUAL INFLUENCE OF SCIENCE. The influence of science on modern civilization has been twofold: 1. Intellectual; 2. Economical. Under these titles we may conveniently consider it.

Intellectually it overthrew the authority of tradition. It refused to accept, unless accompanied by proof, the dicta of any master, no matter how eminent or honored his name. The conditions of admission into the Italian Accademia del Cimento, and the motto adopted by the Royal Society of London, illustrate the position it took in this respect.

It rejected the supernatural and miraculous as evidence in physical discussions. It abandoned sign-proof such as the Jews in old days required, and denied that a demonstration can be given through an illustration of something else, thus casting aside the logic that had been in vogue for many centuries.

In physical inquiries, its mode of procedure was, to test the value of any proposed hypothesis, by executing computations in any special case on the basis or principle of that hypothesis, and then, by performing an experiment or making an observation, to ascertain whether the result of these agreed with the result of the computation. If it did not, the hypothesis was to be rejected.

We may here introduce an illustration or two of this mode of procedure:

THEORIES OF GRAVITATION AND PHLOGISTON. Newton, suspecting that the influence of the earth's attraction, gravity, may extend as far as the moon, and be the force that causes her to revolve in her orbit round the earth, calculated that, by her motion in her orbit, she was deflected from the tangent thirteen feet every minute; but, by ascertaining the space through which bodies would fall in one minute at the earth's surface, and supposing it to be diminished in the ratio of the inverse square, it appeared that the attraction at the moon's orbit would draw a body through more than fifteen feet. He, therefore, for the time, considered his hypothesis as unsustained. But it so happened that Picard shortly afterward executed more correctly a new measurement of a degree; this changed the estimated magnitude of the earth, and the distance of the moon, which was measured in earth-semidiameters. Newton now renewed his computation, and, as I have related on a previous page, as it drew to a close, foreseeing that a coincidence was about to be established, was so much agitated that he was obliged to ask a friend to complete it. The hypothesis was sustained.

A second instance will sufficiently illustrate the method under consideration. It is presented by the chemical theory of phlogiston. Stahl, the author of this theory, asserted that there is a principle of inflammability, to which he gave the name phlogiston, having the quality of uniting with substances. Thus, when what we now term a metallic oxide was united to it, a metal was produced; and, if the phlogiston were withdrawn, the metal passed back into its earthy or oxidized state. On this principle, then, the metals were compound bodies, earths combined with phlogiston.