The second point to be considered is the method adopted by Spinoza for setting forth his philosophy; it is the demonstrative method of geometry as employed by Euclid, in which we find definitions, explanations, axioms, and theorems. Even Descartes made it his starting-point that philosophic propositions must be mathematically handled and proved, that they must have the very same evidence as mathematics. The mathematical method is considered superior to all others, on account of the nature of its evidence; and it is natural that independent knowledge in its re-awakening lighted first upon this form, of which it saw so brilliant an example. The mathematical method is, however, ill-adapted for speculative content, and finds its proper place only in the finite sciences of the understanding. In modern times Jacobi has asserted (Werke, Vol. IV. Section I. pp. 217-223) that all demonstration, all scientific knowledge leads back to Spinozism, which alone is a logical method of thought; and because it must lead thither, it is really of no service whatever, but immediate knowledge is what we must depend on. It may be conceded to Jacobi that the method of demonstration leads to Spinozism, if we understand thereby merely the method of knowledge belonging to the understanding. But the fact is that Spinoza is made a testing-point in modern philosophy, so that it may really be said: You are either a Spinozist or not a philosopher at all. This being so, the mathematical and demonstrative method of Spinoza would seem to be only a defect in the external form; but it is the fundamental defect of the whole position. In this method the nature of philosophic knowledge and the object thereof, are entirely misconceived, for mathematical knowledge and method are merely formal in character and consequently altogether unsuited for philosophy. Mathematical knowledge exhibits its proof on the existent object as such, not on the object as conceived; the Notion is lacking throughout; the content of Philosophy, however, is simply the Notion and that which is comprehended by the Notion. Therefore this Notion as the knowledge of the essence is simply one assumed, which falls within the philosophic subject; and this is what represents itself to be the method peculiar to Spinoza's philosophy.

If Spinoza had in fact tried to construct his philosophical system by the method that our contemporary positivism would have recommended to him, it is not difficult to imagine what he would have produced as a ‘system’. He would only have brought together the purely mechanical and religious, mystical ‘general ideas’ that were guiding all (or almost all) naturalists in his day. Spinoza understood very clearly that religious, theological mysticism was the inevitable complement of a purely mechanistic (geometrical, mathematical) world outlook, i.e. the point of view that considers the sole ‘objective’ properties of the real world to be only the spatial, geometrical forms and relations of bodies. His greatness was that he did not plod along behind contemporaneous natural science, i.e. behind the one-sided, mechanistic thinking of the coryphaei of the science of the day, but subjected this way of thinking to well substantiated criticism from the angle of the specific concepts of philosophy as a special science. This feature of Spinoza’s thinking was brought out clearly and explicitly by Friedrich Engels: ‘It is to the highest credit of the philosophy of the time that it did not let itself be led astray by the restricted state of contemporary natural knowledge, and that from Spinoza right to the great French materialists it insisted on explaining the world from the world itself and left the justification in detail to the natural science of the future.’ [Dialectics of Nature] That is why Spinoza has come down in the history of science as an equal contributor to its progress with Galileo and Newton, and not as their epigone, repeating after them the general ideas that could be drawn from their work. He investigated reality himself from the special, philosophical angle, and did not generalise the results and ready-made findings of other people’s investigation, did not bring together the general ideas of the science of his day and the methods of investigation characteristic of it, or the methodology and logic of his contemporary science. He understood that that way led philosophy up a blind alley, and condemned it to the role of the wagon train bringing up in the rear of the attacking army the latter’s own ‘general ideas and methods’, including all the illusions and prejudices incorporated in them. That is why he also developed ‘general ideas and methods of thought’ to which the natural science of the day had not yet risen, and armed future science with them, which recognised his greatness three centuries later through the pen of Albert Einstein, who wrote that he would have liked ‘old Spinoza’ as the umpire in his dispute with Niels Bohr on the fundamental problems of quantum mechanics rather than Carnap or Bertrand Russell, who were contending for the role of the ‘philosopher of modern science’ and spoke disdainfully of Spinoza’s philosophy as an ‘outmoded’ point of view ‘which neither science nor philosophy can nowadays accept’. Spinoza's understanding of thinking as the activity of that same nature to which extension also belonged is an axiom of the true modern philosophy of our century, to which true science is turning more and more confidently and consciously in our day (despite all the attempts to discredit it) as the point of view of true materialism.

According to Spinoza’s system, all reality flows with strict necessity from the nature of God. With the geometrical method, Spinoza captures the structure of this reality by deducing philosophical conclusions about reality from definitions which express the nature of God.

The primary method of mathematics is deduction; the primary method of philosophy is descrip- [16] tive generalization. Under the influence of mathematics, deduction has been foisted onto philosophy as its standard method, instead of taking its true place as an essential auxiliary mode of verification whereby to test the scope of generalities. This misapprehension of philosophic method has veiled the very considerable success of philosophy in providing generic notions which add lucidity to our apprehension of the facts of experience. The depositions of Plato, Aristotle, Thomas Aquinas, Descartes, Spinoza, Leibniz,† Locke, Berkeley, Hume, Kant, Hegel, merely mean that ideas which these men introduced into the philosophic tradition must be construed with limitations, adaptations, and inversions, either unknown to them, or even explicitly repudiated by them. A new idea introduces a new alternative; and we are not less indebted to a thinker when we adopt the alternative which he discarded. Philosophy never reverts to its old position after the shock of a great philosopher.

The shortcoming thus acknowledged to attach to the content turns out at the same time to be a shortcoming in respect of form. Spinoza puts substance at the head of his system, and defines it to be the unity of thought and extension, without demonstrating how he gets to this distinction, or how he traces it back to the unity of substance. The further treatment of the subject proceeds in what is called the mathematical method. Definitions and axioms are first laid down: after them comes a series of theorems, which are proved by an analytical reduction of them to these unproved postulates. Although the system of Spinoza, and that even by those who altogether reject its contents and results, is praised for the strict sequence of its method, such unqualified praise of the form is as little justified as an unqualified rejection of the content. The defect of the content is that the form is not known as immanent in it, and therefore only approaches it as an outer and subjective form. As intuitively accepted by Spinoza without a previous mediation by dialectic, Substance, as the universal negative power, is as it were a dark shapeless abyss which engulfs all definite content as radically null, and produces from itself nothing that has a positive subsistence of its own.

What also fascinated me about Spinoza was his philosophical strategy. Jacques Derrida has spoken a lot about strategy in philosophy, and he is perfectly right, since every philosophy is a dispositif of theoretical combat that disposes of theses as so many strongholds or prominent places so as to be able, in its aim and strategic attacks, to take over the theoretical places fortified and occupied by the adversary. Yet Spinoza began with God! [...] A supreme strategy: he began by taking over the chief stronghold of his adversary, or rather he established himself there as if he were his own adversary, therefore not suspected of being the sworn adversary, and redisposed the theoretical fortress in such a way as to turn it completely around, as one turns around cannons against the fortress's own occupant.

Spinoza is a highly systematic thinker, but still I do not think I can offer a single key for all things Spinozistic. Personally, one thing which got me excited about Spinoza is his philosophical boldness, i.e., his willingness to pursue philosophical exploration as far as he can, making very little concessions to commonly accepted beliefs and norms. In terms of content, I take his attempt to conceive of God, nature, and ethics in a manner that is free from anthropomorphism and anthropocentric illusions as one of the deepest elements of his philosophical thinking. A closely related issue is his advocacy of actual infinity (an issue that has been mostly neglected in recent literature). Finally, the very attempt to do philosophy systematically (rather than rely on fragmented and disassociated intuitions) and transparently (laying bare the logical structure of his arguments) commands my respect, indeed admiration.

As regards the philosophy of Spinoza, it is very simple, and on the whole easy to comprehend; the difficulty which it presents is due partly to the limitations of the method in which Spinoza presents his thoughts, and partly to his narrow range of ideas, which causes him in an unsatisfactory way to pass over important points of view and cardinal questions. Spinoza's system is that of Descartes made objective in the form of absolute truth. The simple thought of Spinoza's idealism is this: The true is simply and solely the one substance, whose attributes are thought and extension or nature: and only this absolute unity is reality, it alone is God. It is, as with Descartes, the unity of thought and Being, or that which contains the Notion of its existence in itself. The Cartesian substance, as Idea, has certainly Being included in its Notion; but it is only Being as abstract, not as real Being or as extension (supra, p. 241). With Descartes corporeality and the thinking 'I' are altogether independent Beings; this independence of the two extremes is done away with in Spinozism by their becoming moments of the one absolute Being. This expression signifies that Being must be grasped as the unity of opposites; the chief consideration is not to let slip the opposition and set it aside, but to reconcile and resolve it. Since then it is thought and Being, and no longer the abstractions of the finite and infinite, or of limit and the unlimited, that form the opposition (supra, p. 161), Being is here more definitely regarded as extension; for in its abstraction it would be really only that return into itself, that simple equality with itself, which constitutes thought (supra, p. 229). The pure thought of Spinoza is therefore not the simple universal of Plato, for it has likewise come to know the absolute opposition of Notion and Being.

An immense role in the development of logic, and in preparing the ground for modern views on its subject matter, a role far from fully appreciated, was played by Spinoza. Like Leibniz, Spinoza rose high above the mechanistic limitations of the natural science of his time. Any tendency directly to universalise partial forms and methods of thinking only useful within the bounds of mechanistic, mathematical natural science was also foreign to him. Insofar as logic was preserved alongside the doctrine of substance, Spinoza treated it as an applied discipline by analogy with medicine, since its concern proved not to be the invention of artificial rules but the co-ordination of human intellect with the laws of thought understood as an ‘attribute’ of the natural whole, only as ‘modes of expression’ of the universal order and connection of things. He also tried to work out logical problems on the basis of this conception. Spinoza understood thought much more profoundly and, in essence, dialectically, which is why his figure presents special interest in the history of dialectics; he was probably the only one of the great thinkers of the pre-Marxian era who knew how to unite brilliant models of acutely dialectical thought with a consistently held materialist principle (rigorously applied throughout his system) of understanding thought and its relations to the external world lying in the space outside the human head. The influence of Spinoza's ideas on the subsequent development of dialectical thought can hardly be exaggerated. ‘It is therefore worthy of note that thought must begin by placing itself at the standpoint of Spinozism; to be a follower of Spinoza is the essential commencement of all Philosophy.’ [Lectures on the History of Philosophy, Hegel]

...We must mention the providential man who, at the same time as Locke and Leibnitz, had educated himself in the school of Descartes, had for a long time been viewed only with scorn and hatred, and who nevertheless today is rising to exclusive supremacy in the world of intellect. I am speaking about Benedict Spinoza. One great genius shapes himself by means of another, less through assimilation than through friction. One diamond polishes the other. Thus Descartes' philosophy did not originate, but merely furthered, Spinoza's. Hence we find in the pupil, first of all, the method of the master; this is a great gain. We also find in Spinoza, as in Descartes, a method of demonstration borrowed from mathematics. This is a great defect. The mathematical form gives Spinoza's work a harsh exterior. But this is like the hard shell of the almond; the kernel is all the more delightful. On reading Spinoza we are seized by an emotion similar to that which we feel at the sight of great Nature in her most animated composure. A forest of heaven‑aspiring thoughts whose blossoming treetops are tossing like waves, while the immovable trunks are rooted in the eternal earth. There is a certain mysterious aura about Spinoza's writings. The air of the future seems to flow over us. Perhaps the spirit of the Hebrew prophets still hovered over their late‑born descendant. There is, withal, a seriousness in him, a confident pride, a solemn dignity of thought, which also seem to be a part of his inheritance; for Spinoza belonged to one of those martyr families exiled from Spain by the most Catholic of kings. Added to this is the patience of the Hollander, which was always revealed in the life of the man as well as in his writings. It is a fact that Spinoza's life was beyond reproach and pure and spotless as the life of his divine cousin, Jesus Christ. Like Him, he too suffered for his teachings; like Him he wore the crown of thorns. Wherever a great mind expresses its thought, there is Golgotha.

Spinoza founds Modern materialism in its highest form, determining the horizons of both Modern and contemporary philosophical speculation within an immanent and given philosophy of being and an atheism defined as the negation of every presupposed ordering of either the constitution of being or human behavior. However, even in its productive and living form, Spinozian metaphysics does not succeed in superseding the limits of a purely "spatial" (or Galilean-physical) conception of the world. It certainly pushes on this conception and tries to destroy its limits, but it does not reach a solution. Rather, it leaves unresolved the problem of the relationship between the spatial dimensions and the temporal, creative, and dynamic dimensions of being. The imagination, that spiritual faculty running throughout the Spinozian system, constitutes being in an order that is only allusively temporal. As such, the problem remains intact, in terms that are unresolved but pure and forceful: Being (before the invention of the dialectic) evades the tangle of dialectical materialism. In fact, the readings of Spinoza by socialist and Soviet authors have not enriched dialectical materialism but have, rather, only diminished the potentialities that Spinozian metaphysics offers for superseding the purely spatial and objectivistic dimension of materialism.

Spinoza’s metaphysics is, in many ways, an effort to tap into the underlying rationalist motivations of Descartes’s metaphysics and to follow through on these motivations more consistently than Descartes ever did. Employing the Cartesian notions of substance, attribute, and mode, and wielding strongly rationalist principles only hinted at in Descartes—such as the PSR and the Principle of the Identity of Indiscernibles—Spinoza is able to mount a powerful argument for substance monism, for the view that there is, fundamentally, only one thing in the world.

Spinoza is the clear and luminous side of Modern philosophy. He is the negation of bourgeois mediation and of all the logical, metaphysical, and juridical fictions that organize its expansion. He is the attempt to determine the continuity of the revolutionary project of humanism. With Spinoza, philosophy succeeds for the first time in negating itself as a science of mediation. In Spinoza there is the sense of a great anticipation of the future centuries; there is the intuition of such a radical truth of future philosophy that it not only keeps him from being flattened onto seventeenth-century thought but also, it often seems, denies any confrontation, any comparison. Really, none of his contemporaries understands him or refutes him.

Just as Hegel later developed the metaphysical and rationalistic bases of the Spinoza philosophy giving the only possible refutation to Spinozism, that is, by converting the substance of Spinoza into an absolute idea, into the absolute spirit, and in this way, presented an antithesis to Spinozist teaching, so in his time, Spinoza presented an antithesis with respect to Descartes, but a materialistic antithesis.