For what Descartes had stated in an exclusively _ideal_ and _subjective_ sense, _i.e._, only for us, for _cognitive purposes_--in this instance for the sake of proving the existence of God--Spinoza took in a _real_ and _objective_ sense, as the actual relation of God to the world. According to Descartes, the existence of God is contained in the _conception_ of God, therefore it becomes an argument for his actual being: according to Spinoza, God is himself contained in the world. Thus what, with Descartes, was only reason of knowledge, becomes, with Spinoza, reason of fact. If the former, in his Ontological Proof, taught that the _existentia_ of God is a consequence of the _essentia_ of God, the latter turns this into _causa sui_, and boldly opens his Ethics with: _per causam sui intelligo id, cujus essentia_ (conception) _involvit existentiam_, remaining deaf to Aristotle's warning cry, τὸ δ' εἶναι οὐκ οὐσία οὐδενί! Now, this is the most palpable confusion of _reason_ and _cause_. And if Neo-Spinozans (Schellingites, Hegelians, &c.), with whom words are wont to pass for thoughts, often indulge in pompous, solemn admiration for this _causa sui_, for my own part I see nothing but a _contradictio in adjecto_ in this same _causa sui_, a _before_ that is _after_, an audacious command to us, to sever arbitrarily the eternal causal chain--something, in short, very like the proceeding of that Austrian, who finding himself unable to reach high enough to fasten the clasp on his tightly-strapped shako, got upon a chair. The right emblem for _causa sui_ is Baron Münchhausen, sinking on horseback into the water, clinging by the legs to his horse and pulling both himself and the animal out by his own pigtail, with the motto underneath: _Causa sui_. Let us finally cast a look at the 16th proposition of the 1st book of the Ethics. Here we find Spinoza concluding from the proposition, _ex data cujuscunque rei definitione plures proprietates intellectus concludit, quæ revera ex eadem necessario sequuntur, that ex necessitate divinæ, naturæ_ (_i.e._, taken as a reality), _infinita infinitis modis sequi debent_: this God therefore unquestionably stands in the same relation to the world as a conception to its definition. The corollary, _Deum omnium rerum esse_ CAUSAM EFFICIENTEM, is nevertheless immediately connected with it. It is impossible to carry the confusion between reason and cause farther, nor could it lead to graver consequences than here. But this shows the importance of the subject of the present treatise.