While we can understand the indignation of the devout believers at the contemptuous destruction of sacred relics for the sake of the caskets in which they were contained, we can hardly regret the disappearance of the so-called sacred objects themselves. But it is otherwise with the destruction of books. The professors of Islam, whatever may have been their conduct in regard to particular libraries, have usually held the all-sufficiency of the Koran. That which contradicts its teaching ought to be destroyed; that which is in accordance with it is superfluous. The libraries of the churches, whatever Mahomet himself may have believed, were to the ignorant fanatical masses which followed him anti-Islamic. The only value of books was the amount for which they could be sold. Critobulus says that not only the holy and religious books, but also those treating of profane sciences and of philosophy, were either thrown into the fire or trampled irreverently under foot, but that the greater part were sold--not for the sake of the price but in mockery--for two or three pence or even farthings.[477] The ships of the Turkish fleet had among their cargo, says Ducas, an innumerable quantity of books.[478] In the booty collected by the Turks they were so plentiful and cheap, that for a nummus--probably worth sixpence--ten volumes were sold containing the works of Plato and Aristotle, treatises on theology and other sciences. Christian and Moslem writers agree in stating that the sack of the city continued, as Mahomet had promised, for three days. Khodja Sad-ud-din, after affirming that the soldiers of Islam ‘acted in accordance with the precept, “Slaughter their aged and capture their youth,”’ adds, with the Oriental imagery of Turkish historians: ‘For three days and nights there was, with the imperial permission, a general sack, and the victorious troops, through the richness of the spoil, entwined the arm of possession round the neck of their desires, and by binding the lustre of their hearts to the locks of the damsels, beautiful as houris, and by the sight of the sweetly smiling fair ones, they made the eye of their hopes the participator in their good fortune.’[479] It must, however, not be forgotten that although those who took the principal part in the sack were Mahometans, yet there were also no small numbers of Christian renegades.[480] [Sidenote: Numbers killed or captured.] As to the number of persons captured or killed, the estimates do not greatly differ. Leonard states that sixty thousand captives were bound together preparatory to their final distribution. In such circumstances exaggeration is usual and almost unavoidable. But Critobulus, writing some years afterwards, estimates that the number of Greeks and Italians killed during the siege and after the capture was four thousand, that five hundred of the army and upwards of fifty thousand of the rest of the population were reduced to slavery.[481]