Nevertheless, universal empire was altogether in accord with the spirit of the faith. ‘When a people leaveth off to fight in the ways of the Lord,’ said Abu Bekr in his inaugural address (and, in saying it, struck the key-note of Islam), ‘the Lord casteth off that people.’ And so, when the Rubicon, the border land of Arabia, was once crossed, the horizon enlarged in ever-widening circles, till it embraced the world. Now indeed the marauding spirit of the Bedouin was in unison with the militant spirit of Islam. The cry of plunder and of conquest reverberated throughout the land, and was answered eagerly. The movement began naturally with the tribes in the north which had been first reclaimed from their apostasy, and whose restless spirit led them over the frontier. Later on, in the second year of the Caliphate, the exodus spread to the people of the south. At first the Caliph forbade that help should be taken from such as had backslidden. The privilege of fighting for the faith was reserved for those who had remained firm in its profession. But, step by step, as new spheres opened out, and the cry ran through the land for fresh levies to fill up the ‘martyr’ gaps, the ban was put aside, and all were welcome. Warrior after warrior, column after column, whole tribes in endless succession, with their women and children, issued forth to battle. And ever, at the marvellous tale of cities conquered, of booty rich beyond compute, of fair captives distributed on the field--‘to every man a damsel or two,’ and, above all, at the sight of the royal Fifth of spoil and slaves sent to Medîna--fresh tribes arose and went. Onward and still onward, like swarms from the hive, one after another they poured forth, pressed first to the north, and spread thence in great masses to the east and west. [Sidenote: Discredit still attaching to apostasy.] It must not, however, be overlooked that though apostasy was thus condoned, and in the blaze of victory almost forgotten, a certain discredit still clung to the backslider. His guilt was not like that of others who had committed sins, however black, ignorantly before conversion. The apostate, having been once enlightened, cast by his fall a deliberate slur upon Islam. And therefore no chief who had joined the great apostasy was ever promoted to a chief command. He might fight, and was welcome, in the ranks, and was even allowed to head small parties of fifty or a hundred; but to the last the post of leader was denied him. [Sidenote: Slaves of Arab blood set free.]