Mr. Wells is further much to be congratulated upon his contrast between the universality of writing and reading in the world of Arabic culture at its height, and the lack of them in the contemporary world of Latin culture, which was, perhaps, the chief external difference between them. He is careful to note (in quoting another authority—and this is an example of his accuracy in detail) the presence of the so-called Arabic numerals in our civilization long before Islam arose. He very justly puts down the development of algebra to Islam, and adds, what is much less known, its possible or probable connection with India. He emphasizes with right judgment the historic function of Islam in creating a flux, as it were, between Asia and Europe and making a passage for ideas between the world east of the old Roman boundary and our world. But where he is most to be congratulated is in his emphasis upon the effect of the Mongol irruption upon Europe, and much more upon the Mohammedan world. It is true that this feature in universal history has long been appreciated. It has been fully present in the minds of historians for more than a lifetime; but an appreciation of it is not yet popularized, and Mr. Wells, writing for a popular audience, has underlined it much more than any other contemporary whom I can call to mind. It would perhaps have been better had he given the origins of the catastrophe (in so far as concerned Islam) with more emphasis. It is true that the horrible Mongolian disaster of the thirteenth century was on another scale, and had ultimately far more effect; but the Turkish beginnings are very important; he gives a short paragraph to the Kahzars (pp. 411–12) who determined the history of Russia—or at any rate _begin_ the determination of it. He very rightly says that the second Turkish branch, the Seljuks, raiding the original Mohammedan Empire of the Near East, was more important. He gives this barely half a page, but he very properly emphasizes the supreme importance of their breaking through the mountain-wall which had hitherto been the defence of our civilization upon the East from the Black Sea to the Levantine coast; and the few lines in which he alludes to the battle of Manzikart and its effect, are striking and just.