The impetus that gave victory to Islam is spent. Since its material prosperity overwhelmed its spiritual ascendancy in the first years of triumph its vitality has waned under the stress of riches, then beneath lassitude and the slow decrease of power. The Prophet Mahomet is at once the glory and bane of his people, the source of their strength and the mainspring of their weakness. He represents more effectively than any other religious teacher the sum of his followers’ spiritual and worldly ideas. His position in religion and philosophy is substantially the position of all his followers; none have progressed beyond the primary thesis he gave to the Arabian world at the close of his career.