In its widest sense "nature" can mean "the totality of things," all that would have to appear in an inventory of the universe. It can also refer to the laws and principles of structure by which the behavior of things may be explained. These two senses cannot be kept independent of each other at any sophisticated level of inquiry, for to state in any of the sciences what an entity is involves describing what it does, its patterns of activity or behavior, and the activity of its constituent elements, as far as they can be known and subsumed under laws.

In a particular philosophical context the sense in which nature is being used can be brought out most clearly by insisting upon the question "What is nature (or the natural) being contrasted with in this context?" In one group of cases the...