INTRODUCTION. 27 



as 1600, regarded magnetism as a force inherent in all matter. 

 So undetermined was even Newton, the profound and expe- 

 rienced thinker, regarding the " ultimate mechanical cause" 

 v.f all motion. 



It is indeed a brilliant effort, worthy of the human mind, to 

 comprise, in one organic whole, the entire science of nature from 

 the laws of gravity to the formative impulse (nisus formativus) 

 in animated bodies ; but the present imperfect state of many 

 branches of physical science offers innumerable difficulties to 

 the solution of such a problem. The imperfectibility of all 

 empirical science, and the boundlessness of the sphere of obser- 

 vation, render the task of explaining the forces of matter 

 by that which is variable in matter, an impracticable one. 

 What has been already perceived by no means exhausts that 

 which is perceptible. If, simply referring to the progress of 

 science in modern times, we compare the imperfect physical 

 knowledge of Gilbert, Robert Boyle, and Hales, with that of 

 the present day, and remember that every few years are 

 characterized by an increasing rapidity of advance, we shall 

 be better able to imagine the periodical and endless changes 

 which all physical sciences are destined to undergo. New 

 substances and new forces will be discovered. 



Although many physical processes, as those of light, heat 

 and electro-magnetism, have been rendered accessible to a 

 mathematical investigation, by being reduced to motion or 

 vibrations, we are still without a solution to those often mooted 

 and perhaps insolvable problems : the cause of chemical 

 differences of matter; the apparently irregular distribution of 

 the planets in reference to their size, density, the inclination 

 of their axes, the eccentricity of their orbits, and the num- 

 ber and distance of their satellites ; the configuration of con- 

 tinents, and the position of their highest mountain chains. 

 Those relations in space, which we have referred to merely 

 by way of illustration, can at piesent be regarded only as 



