Sextus Empiricus presents another forcible instance of the way in which the Ancients were wont universally to confound the logical law of the reason of knowledge with the transcendental law of cause and effect in Nature, persistently mistaking one for the other. In the 9th Book "Adversus Mathematicos," that is, the Book "Adversus Physicos," § 204, he undertakes to prove the law of causality, and says: "He who asserts that there is no cause (αἰτία), either has no cause (αἰτία) for his assertion, or has one. In the former case there is not more truth in his assertion than in its contradiction; in the latter, his assertion itself proves the existence of a cause." By this we see that the Ancients had not yet arrived at a clear distinction between requiring a reason as the ground of a conclusion, and asking for a cause for the occurrence of a real event. As for the Scholastic Philosophers of later times, the law of causality was in their eyes an axiom above investigation: "_non inquirimus an causa sit, quia nihil est per se notius_," says Suarez.[25] At the same time they held fast to the above quoted Aristotelian classification; but, as far as I know at least, they equally failed to arrive at a clear idea of the necessary distinction of which we are here speaking. [25] Suarez, "Disp." 12, sect. 1. § 7. _Descartes._ For we find even the excellent Descartes, who gave the first impulse to subjective reflection and thereby became the father of modern philosophy, still entangled in confusions for which it is difficult to account; and we shall soon see to what serious and deplorable consequences these confusions have led with regard to Metaphysics. In the "_Responsio ad secundas objectiones in meditationes de prima philosophia_," _axioma i._ he says: _Nulla res existit, de qua non possit quæri, quænam sit causa, cur existat. Hoc enim de ipso Deo quæri potest, non quod indigeat ulla causa ut existat, sed quia ipsa ejus naturæ immensitas est_ CAUSA, SIVE RATIO, _propter quam nulla causa indiget ad existendum_. He ought to have said: The immensity of God is a logical reason from which it follows, that God needs no cause; whereas he confounds the two together and obviously has no clear consciousness of the difference between reason and cause. Properly speaking however, it is his intention which mars his insight. For here, where the law of causality demands a _cause_, he substitutes a _reason_ instead of it, because the latter, unlike the former, does not immediately lead to something beyond it; and thus, by means of this very axiom, he clears the way to the _Ontological Proof_ of the existence of God, which was really his invention, for Anselm had only indicated it in a general manner. Immediately after these axioms, of which I have just quoted the first, there comes a formal, quite serious statement of the Ontological Proof, which, in fact, already lies within that axiom, as the chicken does within the egg that has been long brooded over.