The grand feature of Spinoza’s philosophy is that it buries every thing individual and particular, as a finite, in the abyss of the divine substance. With its view unalterably fixed upon the eternal one, it loses sight of every thing which seems actual in the ordinary notions of men. But its defect consists in its inability to transform this negative abyss of substance into the positive ground of all-being and becoming. The substance of Spinoza, has been justly compared to the lair of a lion, which many footsteps enter, but from which none emerge. The existence of the phenomenal world, though it be only the apparent and deceptive reality of the finite, Spinoza does not explain. With his abstract conception of substance he cannot explain it. And yet the means to help him out of the difficulty lay near at hand. He failed to apply universally his fundamental principle that all determination is negation; he applied it only to the finite, but the abstract infinite, in so far as it stands over against the finite, is also a determinate; this infinite must be denied by its negation, which is the case when a finite world is posited. Jacob Boehme rightly apprehended this, when he affirmed, that without a self-duplication, without an ingress into the limited, the finite, the original ground of things is an empty nothing (_cf._ § XXIII. 8). So the original ground of Spinoza is a nothing, a purely indeterminate, because with him substance was only a principle of unity and not also a principle of distinction, because its attributes, instead of being an expression of an actual difference and a positive distinction to itself, are rather wholly indifferent to itself. The system of Spinoza is the most abstract Monotheism that can be thought. It is not accidental that its author, a Jew, should have brought out again this view of the world, this view of absolute identity, for it is in a certain degree with him only a consequence of his national religion—an echo of the Orient.
We have now reached a point of divergence in the development of philosophy. Descartes had affirmed and attempted to mediate the opposition, between thought and being, mind and matter. This mediation, however, was hardly successful, for the two sides of the opposition he had fixed in their widest separation, when he posited them as two substances or powers, which reciprocally negated each other. The followers of Descartes sought a more satisfactory mediation, but the theories to which they saw themselves driven, only indicated the more clearly that the whole premise from which they started must be given up. At length Spinoza abandoned the false notion, and took away its substantiality from each of the two opposed principles. Mind and matter, thought and extension, are now one in the infinite substance. Yet they are not one _in themselves_, which would be the only true unity of the two. That they are one in the substance is of little avail, since they are indifferent to the substance, and are not immanent distinctions in it. Thus even with Spinoza the two remain strictly separate. The ground of this isolation we find in the fact that Spinoza himself did not sufficiently renounce the Cartesian notion, and thus could not escape the Cartesian dualism. With him, as with Descartes, thought is _only_ thought, and extension _only_ extension, and in such an apprehension of the two, the one necessarily excludes the other. If we would find an inner mediation for the two, we must cease to abstract every thing essential from each. The opposite sides must be mediated even in their strictest opposition. To do this, two ways alone were possible. A position could be taken either on the material or on the ideal side, and the attempt made to explain the ideal under the material, or the material under the ideal, comprehending one through the other. Both these attempts were in fact made, and at about the same time. The two parallel courses of a one-sided _idealism_, and a one-sided _realism_ (Empiricism, Sensualism, Materialism), now begin their development.