God or Nature consists of Attributes. God, as the complete system of Attributes, is absolutely infinite or complete; each Attribute is only infinite of its kind. By Attribute Spinoza means an ultimate or irreducible quality or energy. He names two such Attributes, namely, Extension and Thought, but he allows for the possibility of an infinity of Attributes. The Attributes do not belong to, but are identical with, Substance. Reality, moreover, is essentially dynamic, not static—to be is to be doing. Thus the Attribute Extension is really the whole of material energy, and the Attribute Thought is the whole of mind-energy. All material things and events are changing modes or states of Extension; and all mental events or experiences are similarly modifications or states of Thought. Each Attribute exhausts its kind of reality, is an ultimate character, activity or "world-line" of Nature, and gives rise to its entire series of objects and events in accordance with its own laws. These finite objects and events are real enough while they last, but as finite modes they change and pass; not, however, into mere nothingness, for the Attribute, of which they are states, abides. The cosmic process never stops.
Spinoza's conception of Extension and Thought, or Matter and Consciousness, as concurrent Attributes or Energies of Reality cast a new light on the problem of the relation between body and soul. Indeed, it was this problem which led him to the conception of concurrent Attributes. Under the influence of Plato and of Christianity, body and soul had come to be regarded as antago nistic to each other, and their apparently intimate relation caused much perplexity to Cartesians and others. Materialists tried to explain away the soul; idealists sought to explain away the body; the Cartesian Occasionalists fell back on the miraculous inter vention of God to synchronize body and soul (that is, physical and mental processes) like the wire-puller in a Punch and Judy show. Spinoza realized the difference between the mental and the material, but rejected the Cartesian conception of their antago nism. So he did not hesitate to attribute to God both Extension and Thought. And man, a finite mode of God, is thus both physical and mental, and functions in both ways concurrently, even if each series of events is self-contained. This solution committed Spinoza to the view that all physical beings are animated, though in very different degrees ; and Spinoza accepted this view.
Theory of Knowledge.—Spinoza commenced a treatise spe cially devoted to the problem of Knowledge. But this work, the Treatise on the Improvement of the Understanding, was never completed. In his other works epistemological discussions are intimately linked with the rest of his philosophy. Indeed, even in the Treatise on the Improvement of the Understanding epis temological views are almost inseparably connected with ethical and religious ones. That is the consequence of his characteristic conception of "Knowledge." For Spinoza "Knowledge" is "life," not in the sense that contemplation is the highest life, but in the sense that knowledge is the means of holding together the threads of life in a systematic unity that can fill its proper place in the cosmic system. In this sense the effort after the highest knowledge
becomes part of the cosmic activities by which cosmic unity is maintained, and so part of the very life of God. There are two things which must be borne in mind in connection with Spinoza's conception of knowledge. The first is his insistence on the active character of knowledge. The ideas or concepts by means of which thought construes reality are not like "lifeless pictures on a panel"; they are activities by which reality is apprehended; they are part of reality, and reality is activity. The second point is that Spinoza does not divorce knowing from willing. Man always acts according to his lights. If a man's endeavours appear to fall short of his knowledge, that is only because his knowledge is not really what it is held to be, but is wanting in some respect. On the one hand, reason, for Spinoza, is essentially the "practical reason." On the other hand, the highest expression of willing is experienced in that striving for consistency and harmony which is so characteristic of reason. For Spinoza, then, as for Bacon and all the Renaissance thinkers, "Knowledge is power," but in a much deeper sense than Bacon intended.
Spinoza's account of knowledge is particularly interesting as a clue to the way in which he gradually built up his ontology. He distinguishes three ascending grades of knowledge, namely, opinion, reason and intuition. By "opinion" Spinoza means the lowest grade of knowledge in which one assents to what one hears, perceives or imagines. It is the pre-scientific stage of knowledge. Its main characteristic is that objects and events are apprehended as detached things, without any insight into their connections or laws. The second grade, or "reason," is that in which we have an insight into the connections of things and events, and their laws; it is the stage of scientific knowledge. This grade of knowledge is greatly superior to the first, inasmuch as a knowledge of their connections and laws makes things more intelligible. But even this stage is imperfect because rather abstract. It reveals the course of single threads in the fabric of reality, not the whole pattern; it traces "world-lines," but affords no synoptic vision of the cosmos as a whole. It is the function of the third grade of knowledge, "intuition," to complete the scheme. In intuitive knowledge the cosmic system is grasped as a whole. This highest stage is only possible for a mind that has been through the discipline of the rational stage. Unlike the mystics, Spinoza does not regard intuitive vision as a substitute for thought and entirely different from it, but rather as its highest fruit—it is "thoughtfulness matured to inspiration." The three stages of knowledge might be roughly compared with the three stages in the acquisition of the knowledge of a new language.