'^00 COSMOS. 



INVASION OF THE ARABS— INTELLECTUAL APTITUDE OF THIS BRANCH 

 OF THE SEMITIC RACES.— INFLUENCE OF FOREIGN ELEMENTS ON 

 THE DEVELOPMENT OF EUROPEAN CULTURE.— THE INDIVIDUALITY 

 OF THE NATIONAL CHARACTER OF THE ARABS.— TENDENCY TO A 

 COMMUNION WITH NATURE AND PHYSICAL FORCES.— MEDICINE AND 

 CHEMISTRY.— EXTENSION OF PHYSICAL GEOGRAPHY.— ASTRONOMY 

 AND MATHEMATICAL SCIENCES IN THE INTERIOR OF CONTINENTS 



In the preceding sketch of the history of the physical con 

 templation of the universe we have already considered four 

 principal momenta in the gradual development of the recog- 

 nition of the unity of nature, viz. : 



1 . The attempts made to penetrate from the basin of the 

 Mediterranean eastward to the Euxine and Phasis ; south- 

 ward to Ophir and the tropical gold lands; and westward, 

 through the Pillars of Hercules, into the " all-encircling 

 ocean." 



2. The Macedonian campaign under Alexander the Great. 



3. The age of the Ptolemies. 



4. The universal dominion of the Romans. 



We now, therefore, proceed to consider the important influ- 

 ence exercised on the general advancement of the physical and 

 mathematical sciences, first, by the admixture of the foreign 

 elements of Arabian culture with European civilization, and, 

 six or seven centuries later, by the maritime discoveries of the 

 Portuguese and Spaniards ; and likewise their influence on 

 the knowledge of the earth and the regions of space, with re- 

 spect to form and measurement, and to the heterogeneous 

 nature of matter, and the forces inherent in it. The dis- 

 covery and exploration of the New Continent, through the 

 range of its volcanic Cordilleras and its elevated plateaux, 

 where climates are ranged in strata, as it were, above one 

 another, and the development of vegetation within 120 de- 

 grees of latitude, undoubtedly indicates the period which has 

 presented, in the shortest period of time, the greatest abund- 

 ance of new physical observations to the human mind. 



From this period, the extension of cosmical knowledge 

 ceased to be associated with separate and locally-defined polit- 

 ical occurrences. Great inventions now first emanated from 

 spontaneous intellectual power, and were no longer solely 

 excited by the influence of separate external causes. The 

 human mind, acting simultaneously in several directions, 

 created, by new combinations of thought, new organs, by 

 which the human eye could alike scrutinize the remote re 



