Everything that exists has a specific identity and a specific nature that determines how it acts.
Nature is to be explained in terms of nature, without reference to the supernatural.
Everything that occurs has a material cause, and everything that exists has a material basis. The mind apprehends reality through a process of reasoning. Reasoning is the art of building from perceptions to concepts and propositions. In this way, beliefs are built up from the evidence. Reasoning, or logic, follows certain, non-arbitrary rules which must be adhered to if we wish to reach valid conclusions.