If, however, any one cavils at our argument, on the ground that by not admitting the difference of nature it leads to a mixture and confusion of the Persons, we shall make to such a charge this answer;—that while we confess the invariable character of the nature, we do not deny the difference in respect of cause, and that which is caused, by which alone we apprehend that one Person is distinguished from another;—by our belief, that is, that one is the Cause, and another is of the Cause; and again in that which is of the Cause we recognize another distinction. For one is directly from the first Cause, and another by that which is directly from the first Cause; so that the attribute of being Only-begotten abides without doubt in the Son, and the interposition of the Son, while it guards His attribute of being Only-begotten, does not shut out the Spirit from His relation by way of nature to the Father.