virtue of some single fact are also derived from pragmatic. Examples of this, which have also become proverbial, because they refer to concepts that have been persistently criticized by the historians of our time, are the fall of the Roman Empire, explained as the result of barbarian invasions, European civilization of the twelfth and thirteenth centuries, as the result of the Crusades, the renascence of classical literatures, as the result of the Turkish conquest of Constantinople and of the immigration of the learned Byzantines into Italy--and the like. And in just the same way as when the conception of the single individual did not furnish a sufficient explanation recourse was for that reason had to a multiplicity of individuals, to their co-operation and conflicting action, so here, when the sole cause adduced soon proved itself too narrow, an attempt was made to make up for the insufficiency of the method by the search for and enumeration of multiple historical causes. This enumeration threatened to proceed to the infinite, but, finite or infinite as it might be, it never explained the process to be explained, for the obvious reason that the continuous is never made out of the discontinuous, however much the latter may be multiplied and solidified. The so-called theory of the causes or factors of history, which survives in modern consciousness, together with several other mental habits of pragmatic, although generally inclined to follow other paths, is rather a confession of powerlessness to dominate history by means of individual causes, or causes individually conceived, than a theory; far from being a solution, it is but a reopening of the problem.