16 INTRODUCTION. 



of mutually dependent quantities, by supposing them to vary, and 

 observing their relative changes, was the last and highest step in 

 Mathematics. 



In analyzing the material world, we first observe the great distinc- 

 tion between animate and inanimate bodies : the latter having no in- 

 nate principle of life, nor power to move or act, or cease from action, 

 except when influenced by some external cause, or force. The study 

 of these forces and their laws of action is the object of Natural Phi- 

 losophy ; which shows us, that light, heat, and electricity, even 

 clouds and storms, lightning and thunder, are all subject to the same 

 general laws ; and that the stars of heaven, rolling on through countless 

 ages, with the earth itself, the star which we inhabit, obey, in all their 

 motions, the simple law of gravitation, which causes the uplifted 

 stone to fall to the ground. Before leaving inanimate matter, it re- 

 mains to consider its composition : and we find in it an immense 

 variety of compounds, all resulting from a few simple elements. This 

 leads to the study of the means by which those elements may be 

 compounded or disunited, with the nature and uses both of the ele- 

 ments and of their compounds ; in all of which consists the science 

 of Chemistry. 



In studying animated nature, we find a principle of life, modifying 

 the laws of inanimate matter. Hence we have a new class of pheno- 

 mena, in the origin, growth, and decay of organic bodies, whether 

 plants or animals ; and hence a higher interest attaches to the studies 

 of Botany and Zoology. In the animal races, we find an additional 

 principle of life, inciting them to action, and though far inferior, yet 

 in many respects similar to the human intellect. This principle be- 

 comes more prominent, as we rise to the higher orders of animals ; 

 and as they approach the human race in outward form and physical 

 constitution. The fact that many of these organic forms are found 

 buried in the depths of the earth, here arrests our attention ; and leads 

 us to investigate the structure of our globe ; first in its homogeneous 

 elements, and afterwards in their massive aggregations. Hence arose 

 the sciences of Mineralogy and Geology ; which, in connection with 

 those relating to organic life, complete the range of Natural History. 



Man, being essentially compounded of mind and matter, seems to 

 form the great connecting link between the material and the spiritual 

 world. Considering his material nature, we are first led to study the 

 structure of the human body; especially as affording the means of 

 detecting the diseases to which it is liable, and suggesting their appro- 

 priate remedies. If the study of Medicine originally preceded that 

 of Jlnatomy and Physiology, it could have made, but little progress 

 until these studies were considerably advanced, and some theoretical 

 views adopted concerning the action of remedial agents, by which 

 they might be classified and compared. The Jlrt of Healing was 

 thus improved empirically, until it became a science ; resting on ac- 

 knowledged principles, though of difficult application : and the intro- 

 duction of mechanical agency, or the practice of Surgery, rendered 

 its functions complete. 



The human body, owing to its physical constitution, requires shel- 

 ter, food, and clothing: to supply which, has exercised the ingenuity, 



