Nicene and Post-Nicene Church Fathers Series 2 - The Still Small ...

To Eustathius the physician.
any one give an account of each one of these names, and of the actual nature to which they
are applied, and it will be found that the definition will not in both cases be the same. And
where the definition is not identical the nature is different. There is, then, a distinction to
be observed between the essence, of which no explanatory term has yet been discovered,
and the meaning of the names applied to it in reference to some operation or dignity. That
there should be no difference in the operations we infer from the community of terms. But,
we derive no clear proof of variation in nature, because, as has been said, identity of operations
indicates community of nature. If then Godhead be the name of an operation, we say
that the Godhead is one, as there is one operation of Father, Son, and Holy Ghost; if, however,
as is popularly supposed, the name of Godhead indicates nature, then, since we find no
variation in the nature, we reasonably define the Holy Trinity to be of one Godhead.
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