210 COSMOS. 



estimate by the measurement of magnitudes and the duration 

 of motion. The earUest epoch of such a species of natural ob- 

 servation, although principally limited to organic substances, 

 was the age of Aristotle. There remains a third and higher 

 stage in the progressive advancement of the knowledge of 

 physical phenomena, which embraces an investigation into 

 natural forces, and the powers by which these forces are en- 

 abled to act, in. order to be able to bring the substances liber- 

 ated into new combinations. The means by which this lib 

 eration is effected are experiments, by which phenomena may 

 be called forth at will. 



The last-named stage of the process of knowledge, which 

 was almost wholly disregarded in antiquity, was raised by the 

 Arabs to a high degree of development. This people belong- 

 ed to a country which enjoyed, throughout its whole extent, 

 the climate of the region of palms, and in its greater part that 

 of tropical lands (the tropic of Cancer intersecting the penin- 

 sula in the direction of a line running from Maskat to Mecca), 

 and this portion of the world was therefore characterized by 

 the highly-developed vital force pervading vegetation, by which 

 an abundance of aromatic and balsamic juices was yielded to 

 man from various beneficial and deleterious vegetable sub- 

 stances. The attention of the people must early have been 

 directed to the natural products of their native soil, and those 

 brought as articles of commerce from the accessible coasts of 

 iVIalabar, Ceylon, and Eastern Africa. In these regions of the 

 torrid zone, organic forms become individualized within very 

 limited portions of space, each one being characterized by in- 

 dividual products, and thus increasing the communion of men 

 with nature by a constant excitement toward natural observ- 

 ation. Hence arose the wish to distinguish carefully from one 

 another these precious articles of commerce, v/hich were so 

 important to medicine, to manufactures, and to the pomp of 

 temples and palaces, and to discover the native region of each, 

 which was often artfully concealed from motives of avarice. 

 Starting from the staple emporium of Gerrha, on the Persian 

 Gulf, and from Yemen, the native district of incense, numer- 

 ous caravan tracks intersected the whole interior of the Ara- 

 bian peninsula to Phoenicia and Syria, and thus every where 

 diffused a taste for and a knowledge of the names of these 

 powerful natural products. 



The science of medicine, which was founded by Dioscorides 

 ill the school of Alexandria, when considered with reference to 

 [1.8 scientific development, is essentially a creation of the Arabs, 



