=2. Aristotle’s Two Different Conceptions of Purpose.= Aristotle illustrated his conception of the purposeful relation in nature from two very different types: (1) the development of organisms; (2) the development that takes place when an artisan moulds plastic material. Manifestly here are two different kinds of teleological activities. In organic growth the Form that realizes itself in Matter is immanent in the organism; the artist, on the other hand, superimposes the Form upon the plastic material. In the case of organisms Matter and Form are separable only by abstraction, and are only two aspects of a development which is identical from the beginning to the end; in the case of artistic construction the Matter is first a possibility existing by itself, and the purpose of the artist is later added unto it. In the case of organisms Aristotle speaks of two causes,――the material and the formal; in the case of artistic construction he employs four causes,――the material, the efficient, the formal, and the final. Aristotle did not expressly formulate these two different conceptions of purpose, but he completely applied them in practice. On the one hand he regarded individual things as self-realizing, and on the other he looked upon them as realized in other things. This seemingly harmless difference is really very fundamental, for it is the difference between Aristotle as he meant to be――Aristotle as the critic of Plato’s dualism――and Aristotle who reverts to Plato’s teaching. We find therefore two Aristotles; one a dynamic monist, the other a transcendent dualist. We cannot say that Aristotle as he meant to be is the true Aristotle, for he is a dualist in very many important doctrines. Aristotle’s conception of purpose as exemplified by organisms is his original conception, and is what he intended to be the basis of his philosophy. Here the truly real is the individual determined by its own Form. It is the dynamic and not the artistic view of life. Activity is directed to an end not without but _within itself_. The individual is a complete organic unity at rest within itself. The individual is primarily the essence or substance. Of the ten categories which he enumerates, substance from this point of view is to Aristotle the most important. The nine other categories only describe the states or relations of the substance. The essence of the individual is the substance; and Aristotle conceives the substance as the species or universal in the thing. It is pointed out that even here Aristotle is guilty of a dualism in the double meaning in which he uses substance. But the conception of Aristotle here is of an immanent, dynamic reality. He has in mind the self-contained unity of the individual, whether that be a tree, a man, or the universe.