Some things in nature use other things in nature. Plants use sunlight, whatever nutrients they find in the ground and rainwater; animals use the energy and nutrients gathered from plants and other sources; and human beings use nature to such an extent that they easily fall into thinking that nature has no value or even existence outside of its being used.
The simplest way to account for this use is to posit a single order of natural laws for all that we spoke of above: animals and the nutrients they gather are simply collections of natural things like chemicals and energy. On this account of nature we say that, for example, what plants are doing when they absorb sunlight is that one kind of energy or mass bundle goes into some other mass/ energy bundle according to some set of laws that governs them both. All the actions of plants absorbing nutrients would be seen as the same sort of activity as a flame absorbing oxygen or a set of atoms becoming a molecule. Though I call this the simplest account this is not to make light of it: it took scientists a great many years to get a passable account of nature even in this simplest sense.
But though this simplest account of nature is necessary for a sapiential view of nature, it does not and cannot account for the observation that some things in nature use others. If we try to account for the observed distinction between user and used by a single set of action governing laws for both, then we have to say either that all nature is used, or that nothing is used in nature, and both options are absurd. What is used can be viewed as a tool, and so if there is a single order for all the actions in nature, then either all nature is a set of tools without a tool user or all nature is a tool user that has no tools to use.
1.) The distinction between user and used is the distinction between the living and the non-living. Since the living and the non-living in nature share the same mass/ energy base, but life has something beyond this, we need some name for that-by-which the living goes beyond. The ancient name for this is “soul”, and it only fell out of use rather recently.
2.) If one insists that “nature” means whatever can have its actions unified under a single set of laws, then part of our observing nature involves observing a supernatural element in it. I’m largely indifferent about whether one affirms the antecedent or denies the consequent so long as he adjusts his vocabulary accordingly.
3.) Note that the distinction between user and used is not the sort of thing that one tests. The details of what exactly the user makes use of need to be determined by hypothesis and test (for example, the determination of whether the plant takes is material from the ground or also from the air), but that there is a user at all is a different kind of fact based on another kind of observation.