development! Were this tautology only in question little harm would result; but the misfortune is that, by a too easy confusion, the concept of evolution often emerges, in the hands of the positivists, from the formal emptiness which belongs to it in truth, and acquires a meaning or rather a pretended meaning, very like the meanings of teleology and metaphysics. The almost religious unction and reverence with which one hears the sacred mystery of _evolution_ spoken of gives sufficient proof of this. From such realistic standpoints, now as always, any and every philosophy of history has been criticised. But the very reservations and criticisms of the old mistaken constructions demand a discussion of concepts, that is a process of philosophising: although it may be a philosophising which leads properly to the denial of a philosophy of history. Disputes about method, arising out of the needs of the historian, are added. The works published in recent years embody different investigations of this kind, and in a plainly realistic sense, under the title of _philosophy of history_. Amongst these I will mention as an example a German pamphlet by Simmel, and, amongst ourselves a compendious introduction by Labriola himself. There are, undoubtedly, still philosophies of history which continue to be produced in the old way: voices _clamantium in deserto_, to whom may be granted the consolation of believing themselves the only apostles of an unrecognised truth. Now the materialistic theory of history, in the form in which Labriola states it, involves an entire abandonment of all attempt to establish a law of history, to discover a general concept under which all the complex facts of history can be included. I say 'in the form in which he states it,' because Labriola is aware that several sections of the materialistic school of history tend to approximate to these obsolete ideas. One of these sections, which might be called that of the _monists_, or _abstract materialists_, is characterised by the introduction of metaphysical materialism into the conception of history.