THE PHILOSOPHY OF SPINOZA AND LEIBNIZ. 347 On the one hand, there is no absolute surd, no purely con- tingent thing : on the other hand the surd and the contingent are not absolutely "irrational" or illusory. The surd is reducible to an infinite series, the contingent is the product of an infinity of conditions, and thus each is a form of its other. l Accordingly we may, I think, put the difference between Leibniz and Spinoza in this way, that Spinoza expressly proceeds upon a method of deduction from self-evident first principles, i.e., from a basis of pure identity, while this pro- cedure is possible only because a system of identity in difference is presupposed throughout ; and Leibniz, on the other hand, explicitly recognises this system as practically ultimate, while at the same time he professes to give a shadowy ground for the system itself (a ground of its existence but not of its essence) in the "choice" of God, which is rather a negative release into existence than a positive creation. Thus Spinoza's presupposition of a system of unity in difference as constituting the ultimate reality of things appears in his constant references to the " order and connexion " of things and ideas, to the proximate cause as giving the essence of a thing and to substance as causa sui> natura naturans and natura naturata (i.e, substance as cause and effect, ground and consequent, yet both ultimately the same), to the conatus, effort or tendency in things, to the " series of fixed and eternal things" (universal singulars) 2 and to many similar conceptions. 3 And, on the other hand, Leibniz shows the imperfection of his grasp of the principle which he himself insists upon, by treating the law of sufficient reason as an addition to the law of identity and by speaking of the essences of all abstractly possible worlds as being in the understanding of God, a regio idearum behind the actual world. In short the inconsistencies of the two philosophies 1 Vide Leibniz, Erdinann, 83 b ; Gerhardt, vii., 200 : " The difference be- tween necessary and contingent truths is indeed the same as that between commensurable and incommensurable numbers. For the reduction of commensurable numbers to a common measure is analogous to the demonstration of necessary truths or their reduction to identical truths. But, as in the case of surd ratios the reduction involves an infinite process and yet approaches a common measure, so that a definite but unending series is obtained, thus also contingent truths require an infinite analysis, which God alone can accomplish" (Cf. Cohen, Infinitesimal- Methode, 43). 2 Vide Tractatus de Intellectus Emendatione. 3 E.g., Spinoza uses the very terms in which Leibniz states his principle of sufficient reason : Cujuscunque rei assignari debet causa seu ratio, tarn cur exi&tit, quam cur non existit (Eth., i., 11, demonutr. 2).
