64.5 The events which are associated by us with life are also the situations of physical objects. But the physical object though essential is not an adequate condition for its occurrence. A change in the object almost imperceptible from the physical point of view destroys the life in the succeeding situations of the object. The physical object, as apparent, is a material object and as such is uniform; but when we turn to the causal components of such an object, the apparent character of the whole situation is thereby superseded by the rhythmic quasi-periodic characters of a multitude of parts which are the situations of molecules. In an analogous way we seek for a causal character of the event which in some way or another is apparent to us as alive, and we seek for an expression of this causal character in terms of the causal components of the physical object. It would seem therefore (if the analogy is to be pursued) that apparent life in any situation has, as its counterpart in that situation, more complex, subtler rhythms than those whose aggregate is essential for the physical object. 64.6 Furthermore in the physical object we have in a sense lost the rhythms in the macroscopic aggregate which is the final causal character. But life preserves its expression of rhythm and its sensitiveness to rhythm. Life is the rhythm as such, Whereas a physical object is an average of rhythms which build no rhythm in their aggregation; and thus matter is in itself lifeless. Life is complex in its expression, involving more than percipience, namely desire, emotion, will, and feeling. It exhibits variations of grade, higher and lower, such that the higher grade presupposes the lower for its very existence. This suggests a closer identification of rhythm as the causal counterpart of life; namely, that wherever there is some rhythm, there is some life, only perceptible to us when the analogies are sufficiently close. The rhythm is then the life, in the sense in which it can be said to be included within nature.