684 THE POPULAR SCIENCE MONTHLY! 



tolerated even in a man, much less in a planet, hence the theory of 

 epicycles, or wheels revolving on the rims of other wheels, was 

 introduced. Notwithstanding its questionable parentage, and the 

 fundamental error on which it is based, this theory, as established by 

 Hipparchus and extended by Ptolemy, is about the only example of 

 a scientific working hypothesis previous to the fourteenth century. 



Physics, equally with astronomy, suffered from the anti-scientific 

 method. The study of nature was not only neglected, but discounte- 

 nanced by the Church. A priori arguments were urged against the 

 existence of antipodes, and, but a short time before they were visited 

 by Columbus, a belief in their existence was denounced as heretical. 

 The direction of knowledge during the middle ages was retrogressive 

 rather than progressive. Scholastic physics was based upon the as- 

 sumption that analysis of mental concepts would give all requisite 

 knowledge. Why wonder at the result ? Weight being the cause of 

 bodies falling, it was assumed that heavy bodies would fall faster than 

 light ones. Personal qualities being attributed to inanimate objects, 

 there were supposed to be different degrees of perfection in the metals, 

 and thus arose alchemy, whose aim it was to extract gold the most 

 perfect metal from the baser metals. 



The contagion of scholasticism became epidemic, even infecting 

 able men, and establishing its parasitic growth upon sound theories. 

 Astronomy gave birth to astrology, to whose weird influence even a 

 Bacon could succumb. One of the arguments brought forward in sup- 

 port of the Copei'nican theory was that it placed the noble element, 

 fire, in the center of the universe, thus satisfying the tendency toward 

 mythical explanations. So prevalent was this method of considering 

 nature, that Kepler himself entered into complex speculations concern- 

 ing the relations of music to the motions and distances of the planets ; 

 and even Galileo was led into an erroneous theory of motion in conse- 

 quence of assuming that it must be the simplest possible. In support 

 of true hypotheses, as well as false, metaphysical reasons were given. 

 The fact that from them anything wished for can be proved, consti- 

 tutes the great danger in their use. From the immutable laws of God 

 Descartes deduced the first law of motion, while, from the same source, 

 the Church had previously demonstrated the immovability of the earth. 

 Borelli conjectured that the motions of the planets were controlled by 

 two forces one the centrifugal force, and the other the appetite a 

 planet must have for the body about which it revolves. Suction was 

 explained by the famous principle that Nature abhors a vacuum, and, 

 had it not been discovered that the abhorrence ceased at certain fixed 

 limits, this explanation would probably have done service even to our 

 day, for that class of philosophers for whom the kindred pi-inciple of 

 vitality is a sufiicient explanation of the various phenomena of life. 



The few examples that have been cited give a fair sample of the 

 science of the middle ages. During that long period the men imbued 



