PiiiLOSOPHY OF Botany. -13 



cle to logical proof in an argument, has been, on account of his 

 authority with the faithful, a serious obstacle to the scientific 

 investigations of the truth. His writings mark the turning 

 point in the transformation of the classical philosophical style 

 into the mystic theologic dogmas and hierarchic aspirations 

 of the fifth century. The minds of the people in the Western 

 Empire, as well as in the Eastern Empire, had become so gen- 

 erally and so profoundly occupied with metaphysical mys- 

 ticism, and depraved through the fearful social corruption re- 

 sulting from it. that the love of knowledge fell into disregard 

 and repudiation, and vvas declared nefarious. 



xA.ugustinus died during the siege, and only two days before 

 the storming of Hippo by the Vandals, in the year 430. 



The Vandals, a half-breed of Germanic and Sarmatic blood, 

 had, during the migration of the nations, overrun Spain, and 

 invaded from there the Roman province of Africa. Of all the 

 Germanic tribes they were the most cruel and savage, and 

 their character had been little, or not at all, improved with 

 their adoption of the Christian faith. In 429 they had crossed 

 the straits of Gibraltar under their leader, Geiserich. After a 

 fearful despoliation, lasting about one hundred years, their 

 dominion came to an end through an annihilating defeat, 

 which they sustained at the hand of Belizarius, whom Em- 

 peror Justinian had intrusted with the command of a large 

 army. Africa was now annexed to the Byzantine empire, un- 

 til fate soon again delivered it into other hands. 



In the preceding chapters we left Alexandria silenced by the 

 scymetar, and dismantled, and thus the patriarchate of that 

 city ceased to have any further political influence in the Chris- 

 tian system. In little more than one generation the whole of 

 Northern Africa was converted and speaking Arabic. 



With the rapidity of a storm advanced the forces of Omar. 

 After Syria, Jerusalem, and Egypt had fallen into his hands he 

 determined to advance upon the Roman province of Africa. 

 His successor, Khalifa Abd-Almalik, completed the conquest, 

 intrusting his tried general. Emir Musa, with the conduct of 

 the campaign. Musa completely subjugated the Barbers and 

 retired to the capital of his own province, Kairawan, trans- 



