ESSAYS 31 1 



and the Christianity of this period claimed that its sacred writings contained all 

 knowledge permitted to man. Thus, St. Augustine asserts that there can be no 

 inhabitants on the opposite side of the earth, because no such race is recorded 

 in Scripture. In secular matters the Arabs were more tolerant, and claimed 

 adhesion only to the essential tenets of their religion. They were saved by the 

 innate leaning of Oriental races towards metaphysical speculation, and by the 

 great attention which the climate forced them to pay to sanitary regulations. It 

 was, in the first instance, the medical profession which, as in other periods of 

 history, saved science, but it was primarily a utilitarian science that was fostered, 

 and that soon degenerated. Astronomy became Astrology because men sought 

 divine approbation for their worldly ambitions ; chemistry flourished under the 

 influence of the desire to convert base metal into gold ; and the laws of physics 

 were turned to impress the public mind by the magical powers of the learned. 

 Occasionally, no doubt, a man arose with nobler desires. Such was Mohammed 

 Ben Musa, and above all the astronomer Alhazen (987-1038). It was through 

 the Spanish Moors that science returned to Europe ; but it was alchemy, astrology 

 and magic that mainly found entrance ; and the explosive mixture employed by 

 the Arabs in the display of fireworks was rediscovered, perfected as gunpowder, 

 and used for the destruction of human lives. Whatever there remained of pure 

 science was confined to the teaching of Aristotle. 



A temporary and sporadic revival of learning showed itself in Europe during 

 the thirteenth century, and was coincident with the renascence of art in Italy 

 under Giotto ; but it was short-lived. Roger Bacon's voice remained unheard, 

 though occasionally higher motives prevailed, as when the monk Vitello, one of 

 Bacon's contemporaries, struck by the beauty of the rainbow, investigated the 

 refraction of light. The period, taken as a whole, is singularly depressing. 



It is a relief to turn to the dawn of better days, and once more to note the 

 simultaneous revival of science and art. No better example could be given than 

 that of Leonardo da Vinci (1452-1519), known to the world as a great painter, 

 but also a great man of science. Pure and Applied Science can both claim 

 him as an apostle. Mechanics, according to Leonardo, is the paradise of 

 mathematics, because it brings it to fruition. He was an observer and an 

 experimenter. He recognised that the optical arrangement in the eye was that 

 of the camera obscura ; he investigated the laws of bodies sliding down an inclined 

 plane, but the gem of his experiments, to my mind, is contained in a manuscript 

 notebook preserved in the library of the Louvre. In it we finer the drawing of a 

 long rope stretched out, and the same rope coiled together into spherical shape, 

 with one end protruding a little so that it could be pulled along. A written state- 

 ment first asserts that the coiled-up rope is easier to move than the one stretched 

 out, because the surface of contact is smaller. But directly underneath this it is 

 contradicted, no doubt as the result of an experiment, and it is explained that the 

 pressure is increased in the same proportion as the contact is diminished. This 

 implies, though it is not implicitly stated, that the retarding force is the same in 

 both cases. An important principle in the laws of friction was thus foreshadowed, 

 if not actually enunciated. 



We look to Pure Science for those discoveries or new departures of thought 

 which change the whole mental outlook of the community. Science then becomes 

 international without losing its national influence. Galileo and Darwin supply us 

 with two instances where the search for pure knowledge has led to far-reaching 

 intellectual revolutions. During the interval between the two mental upheavals, 

 great advance in general education had taken place ; the two countries in which 



