“The postulate of exclusive natural causation tells us that natural events can have their causes only in other natural events, and not in conditions lying outside of the continuity of natural causality”; so _W. Wundt_. This is a “postulate, accepted by modern natural science partly tacitly, partly by open profession.” “Even where an exact deduction is not possible, natural science nevertheless acts under this supposition. It never will consider a natural event to be causally explained, if it is attempted to derive that event from other conditions than preceding natural events.” Professor _Jodl_ protests against alliance with the Catholic Church, for the reason that the latter does not acknowledge the fundamental presumption of all scientific research, namely, the uninterrupted natural causation, and because the Church is essentially founded on supernatural presumptions. Prof. _A. Messer_ thinks he has proved sufficiently the untenableness of the Catholic faith by the simple appeal to this presumption: “Natural sciences rest upon the presumption that everything is causally determined. This means, that the same causes must be followed by the same effects, and all natural events take their course according to invariable laws. It is against this presumption that the Church exacts a belief in miracles, in immediate divine manifestations, not explainable by natural causes. _God_ is not a causal factor in the eyes of natural science, because everything, and for that very reason, nothing, could be explained through Him.” We see that the principle is expressly admitted to be a mere presumption. “I concede readily,” says _Paulsen_, “that the law of natural causation is not a proven fact, but a demand or presumption with which reason approaches the task of explaining natural phenomena. But this postulate ... is the hard-fought victory of long scientific effort.... Gradually there were eliminated from the course of nature demoniacal influence and the miraculous intervention of God, and in their stead the idea of natural causation was installed.”