The idea of extension as the gist of physical reality. and of thought as a non-extended reality, Spinoza derived from Descartes. But Descartes made each of these independent substances and conceded to them the power of causal interaction —mind acting upon body and rice versa. Spi noza, as we have seen, makes both forms of reality dependent upon an ultimate substance God—in which is their existence. Furthermore, he denies their power of causal interaction. Cause and effect in his conception are always similar; extension and thought are wholly dis similar: therefore their causal interrelation is impossible. Causation may subsist between indi vidual objects in the attribute extension, that is, between physical bodies, or between individual ideas in the attribute thought, but not between ideas and things. To explain the apparent causal interactions of the latter Spinoza resorted to an elaborate theory of parallelism. Every idea has a physical counterpart in the attribute exten sion; every physical object has its idea. This is not only true for the individuals in each at tribute. but necessarily for their relations also. Hence parallel with every physical causal series there is all ideational causal series reduplicating it : neither is dependent upon the other, but both depend upon the divine substance made manifest through them.
The individuality of things, whether ideas or physical objects. Spinoza explained as particular modes or 'affections' of substance. All particular things in space are the modes of God in the attribute extension; all particular thoughts and feelings are modes of God in the attribute thought. The modes are nature naturata; sub stance or God is naturans. The modes are ephemeral and their existence assumes tem poral form: God is eternal, outlasting all at tributive changes. Particular things, accord ingly, whether of body or mind, are evanescent and finite. All existence is mortal.
Nevertheless there is an indestructible world. It is not to be found in the realm of existences. but in a realm of essences—something wholly different. The Spinozistic conception of essence is most nearly related to the Scholastic concep tion of Ilealisin and to Plato's conception of a world of ideas. It is an hypostatization of the universal aspect of things, that is, of their essen tial nature in a logical or definitive sense, and in many respects is a striking forecast of Hegel's logic of the Absolute. The most distinctive dif ference between Spinoza's world of existences and his world of is that the former exists in time, while the latter has no temporal being. But mortality can pertain only to temporal being; therefore the world of essences. being timeless. must be immortal. Furthermore, the world of essences is a world of immanent being. Every existence has a universal or essential char acter, though to realize this character it must transcend its own intrinsic form, that is, free itself from whatever gives it particularity. The world of essences thus has a kind of being within the world of existences—as the immanent cause of the latter—though it does not share its tem poral limitation. Now this is precisely true of the divine substance; and so it is that the world of essences represents the essential nature of God.
Immanent causation means self-causation, and that which is self-determined is free. From this reasoning Spinoza derived his doctrine of free dom to be won in the world of essences. Existence in the attribute is bondage, for each existent thing is determined by its own causal series; every par ticular object or idea is subject to other objects or ideas, and the form of its being is determined by them. Only in non-temporal, self-caused be
ing, that is. in the universal and immanent, is freedom possible; only by identification with the eternal verities, with substance or God, is im mortality—and with it peace—to be obtained.
From this conception springs Spinoza's ethical doctrine. developed in the third, fourth, and fifth parts of the Ethica,. in its practical form his teaching assumes that everything, so far as in it lies, strives to remain in its own being. The effort by which this striving is manifest is noth ing but the actual essence of the thing. This effort, when it is in the mind alone, is will when in mind and body, it is appetite. if desire is satisfied, we have pleasure; if not, we have sorrow. All affections and emotions resolve into desire, joy, and sorrow, accompanied by ideas. The good is that which we know to be useful, that is, that which we know• to be a means for the nearer attainment of the standard of human nature which is our ideal. Knowledge of good and bad can be a cause in the moral world, counteracting passion and raising us from the world of appetite and mortality to the world of eternal truths.
The passage from mortality to immortality, from bondage to freedom, is made plausible to Spinoza's mind by the fact that every reality has its immanent cause, its universal aspect, or what may be called its cosmological truth. By cultivating steadily this immanent and uni versal nature Man is enabled to realize his im mortal destiny. As to the nature of the initia tive by which a soul in bondage is to alter its course, Spinoza has no clear teaching. The prob lem seems not to have presented itself to him, and indeed this is hardly to be wondered at, since his own mind turned so instinctively to what he conceived to be the divine and the good.
Spinoza's position in the development of philo sophical thought is in many respects unique. He belonged to no school and lie founded none. While in a measure his work was based upon that of his predecessors, it is too strikingly indi vidual to be conceived a mere continuation, even of Cartesian thought. In the vigor and com prehensiveness of his conception, in synthetic daring, he must be ranked with the greatest philo sophical thinkers; and though his system gave rise to no sequential development, he has had perhaps the most pervasive influence of any modern philosopher except Kant. Not only met aphysicians, but poets such as Goethe. Words worth. and Shelley, have gone to him for inspira tion, and the essence of his thought has been in large part appropriated in the poetic pantheism of modern interpretations of nature.
Complete editions of Spinoza's works have been published by Paulus (1802-03). by Bonden (1843-46), and by Van Molten and Land (1882 . English translations have been made for the Bohn Library (1883), by White and Stan lay, the Ethics (London, 1883). by Fullerton, The Philosophy of Spinoza, selections with intro duction (New York, 2d ed. 1894). Of the ex tensive literature especially to be mentioned are: Caird, Spinoza (Edinburgh, MSS) ; :Mar tineau, Study of Spinoza (London. 1882) ; Pollock, Spinoza (2d ed., ib., 1899) ; Fullerton, nn ,cs'pino;:istic Inumortolitq (Philadelphia, 1899) ; Camerer, Die Lchre Spinozas (Stuttgart, 1877) ; Baltzer. Spinozas Ell f wirkclu»gsgang 1SSS) ; Berendt and Friedlander. Spinozas Erkenntnislehre (Berlin, 1891) ; Hoff, Die Staatslehre Spinozas (ib.. 1895) ; Kuno Fischer, Gest-hie/mtc de?. ncucren. Philosophic, I. (Heidel berg, 1S97).