[2] Descartes, Princip. Phil. I. 15: _Magis hoc (ens summe perfectum existere) credet, si attendat, nullius alterius rei ideam apud se inveniri, in qua eodem modo necessariam existentiam contineri animadveriat;--intelliget illam ideam exhibere veram et immutabilem naturam, quaeque non potest non existere, cum necessaria existentia in ea contineatur._ (The reader will be more disposed to _believe_ that there exists a being supremely perfect, if he notes that in the case of nothing else is there found in him an idea, in which he notices necessary existence to be contained in the same way. He will see that that idea exhibits a true and unchangeable nature,--a nature which _cannot but exist,_ since necessary existence is _contained in it._) A remark which immediately follows, and which sounds like mediation or demonstration, does not really prejudice the original principle. In Spinoza we come upon the same statement that the essence or abstract conception of God implies existence. The first of Spinoza's definitions, that of the _Causa Sui_ (or Self-Cause), explains it to be _cujus essentia involvit existentiam, sive id cujus natura non potest concipi nisi existens_ (that of which the essence involves existence, or that whose nature cannot be conceived except as existing). The inseparability of the notion from being is the main point and fundamental hypothesis in his system. But what notion is thus inseparable from being? Not the notion of finite things, for they are so constituted as to have a contingent and a created existence. Spinoza's 11th proposition, which follows with a proof that God exists necessarily, and his 20th, showing that God's existence and his essence are one and the same, are really superfluous, and the proof is more in form than in reality. To say, that God is Substance, the only Substance, and that, as Substance is _Causa Sui,_ God therefore exists necessarily, is merely stating that God is that of which the notion and the being are inseparable. [3] Anselm on the contrary says: _Negligentiae mihi videtur, si post-quam confirmati sumus in fide, non studemus, quod credimus, intelligere._ (Methinks it is _carelessness,_ if, after we have been confirmed in the faith, we do not _exert ourselves to see the meaning of what we believe._) [Tractat. Cur Deus Homo?] These words of Anselm, in connexion with the concrete truths of Christian doctrine, offer a far harder problem for investigation, than is contemplated by this modern faith. CHAPTER VI. LOGIC FURTHER DEFINED AND DIVIDED. 79.] In point of form Logical doctrine has three sides: (α) the Abstract side, or that of understanding: (_ß_) the Dialectical, or that of negative reason: (y) the Speculative, or that of positive reason.