The plenitude of nature and the regularity of the seasons, for example, both attest to the presence of Dao in the world, not as primary substance, and still less a supreme deity, but as pristine order or coherence marked by intelligible patterns of change and principles of operation.
These criteria seem to pull in different directions, the first in favor of particular substances, as the primary substances of the Categories had been particulars, and the second in favor of universals as substances, because they alone are knowable.
There we were given, as examples of primary substances, an individual man or horse, and we learned that a primary substance is "what is neither in a subject nor said of a subject" (2a10).
Thus, Thales considered water as the primary substance and saw all things as "full of gods"; for Anaximenes, air was the universal animating principle of the world, and for Heracleitus it was fire.
If we again accept the distinctions in question as I have drawn them, we should interpret secondary substances as essential characteristics of primary substances.
Secondary substances are related to primary substances as formal principles of the latter.
Indeed, Aristotle offers an argument (2a35 2b7) to establish the primary substances as the fundamental entities in this ontology.
So, it is natural to interpret him as thinking that among primary substances are concrete particulars that are members of natural kinds.
Since Burley conceives of primary substances as the ultimate substrates of existence and subjects of predication in relation to anything else (EP, ch. de substantia, fols. 24va-b, and 25va), the only way to demonstrate the reality of beings in other categories is to treat them as forms and attributes of substances.
The study recruited participants from prison, as the majority of drug users in Swedish prisons report amphetamine as their primary substance of abuse 20.
