A comparison with Spinoza’s conception of the world of nature brings out Leibnitz’s meaning effectively. Both philosophers conceive nature phenomena to be under the law of mechanical causation. To Spinoza, however, all phenomena are qualitatively alike; there are no grades or distinctions of value between them. All are modes of substance and all illusions in the sight of God. To Spinoza phenomena are homogeneous. Leibnitz’s estimate of the world of nature is quite different, and for him nature has a far richer endowment. The phenomena of nature are not homogeneous. Their difference does not consist in their content, but in the degree in which they represent the universe. The law of nature is a unifying principle that gives unitary individuality to the members under the law. The individuality of the terms of the nature-series is implied in the very nature of the law of necessity, and on the other hand, the individual terms, for their part, transform the law of necessity into a principle of unity that is higher than bare necessity. In a necessitated series, Leibnitz points out, each term is determined by the preceding, and in turn each term determines the events that follow. Thus, while nature phenomena are a series and a necessitated series, it is a series whose existence depends upon each event having not only its place, but its unique place. No other event can fill that place, and the conditions that give the event its place constitute its individuality. Every finite event has, so to speak, its formula, and this gives individuality to each term of the series, which appeared to Spinoza only as a homogeneous, mathematical, and characterless mode. Life is meaningful to Leibnitz, because each member of the necessitated series of events has its unique part to play. The changes of life are to Spinoza void of meaning, because he conceives them to be undifferentiated. The law of mechanical necessity became under Leibnitz’s hands a principle of harmony, a teleological principle. Even in the necessitated mathematical series, such as Spinoza conceived the world to be, Leibnitz believed that necessity implies individuality and individuality implies purpose.