Marxism is an integral world-onllook. Expressed in a nutshell, it is contemporary materialism, at present the highest stage in the development of that vieir upon the irorld whose foundations were laid down in ancient Greece by Democritus, and in parl by the Ionian thinkers who preceded that philosopher. What was known as hylozoism was nothing but a naive materialism. \( is to Karl Marx and his friend Frederick Engels that the main credit for the development of present-day materialism must no doubt go. The historical and economic aspects of this world-outlook, i.e., what is known as historical materialism and the closely related sum of views on the tasks, method, and categories of political economy, and on the economic derelopment, of society, especially ca/ iifalist socie/y. are in their fundamentals almost entirely the work of Marx and Engels. Thai which was introduced into these tields by their precursors should be regarded merely as the preparatory work of amassing material, often copious and valuable, hut not as ye I systemalised or illuminated by a single fundamental idea, and therefore riot appraised or utilised in its real significance. What Marx and Engels’ followers in Europe and America have done in these fields is merely a more or less successful elaboration of specific problems, sometimes, it is true, of the utmost importance. That is why the term “Marxism” is often used to signify only these two aspects of the present-day materialist world– outlook not only among the "general public”, who have not yet achieved a deep understanding of philosophical theories, but even among people, both in Russia and the entire civilised world, who Consider themselves faithful followers o[ Marx and Engels. In such cases these two aspects are looked upon as something independent of "philosophical materialism”, and at I imes as something almost opposed to it.  [117•*  And since these two aspects cannot but 118 hang in mid-air when they are torn out of the general context of cognate views constituting their theoretical foundation, those who perform that tearing-out operation naturally feel an urge to "substantiate Marxism" anew by joining it—again quite arbitrarily and most frequently under the influence of philosophical moods prevalent at the time among ideologists of the bourgeoisie— with some philosopher or another: witli Kant. Macli, Avenarins, or Ostwald, and of late with Joseph Dietzgen. True, the philosophical views of J. Dielxgen have arisen quite independently of bourgeois influences and are in considerable measure related to the philosophical views of Marx and Engels. The latter views, bowever, possess an incomparably more consistent and rich content. and for that reason alone cannot be supplemented by Dietzgen’s teachings but can only be popularised by them. No attempts have yet been made to "supplement Marx" with Thomas Aquinas. It is however quite feasible thai, despite the Pope’s recent encyclical against the Modernists, the Catholic world will al some time produce from its midst a thinker capable of performing this feat in ihe sphere of theory.