Science is avowedly empirical in its aim and intent, and its task is that of devising a system of symbols representative of the structure and content of the realm of nature. Hence the logical character of its doctrines will be a reflection of the metaphysical character of its subject-matter. Occurrents make up the stuff of nature. Nature is a complex of occurrents and is, presumably, also itself an occurrent. Relations between occurrents are also occurrents, though they are occurrents of an essentially different kind. However, the difference between relational and non-relational occurrents is inexpressible except by question-begging terms. The existence of relational occurrents is correlative with the fact that there are complex occurrents. For wherever there is a relational occurrent, there is thereby designated a more inclusive occurrent of which the terms and the relation are parts. The most basic and general of all relations between occurrents is that of otherness or difference.