15.  One concise proclamation of our teaching, an inscription intelligible to all, is this people, which so sincerely worships the Trinity, that it would sooner sever anyone from this life, than sever one of the three from the Godhead:  of one mind, of equal zeal, and united to one another, to us and to the Trinity by unity of doctrine.  Briefly to run over its details:  That which is without beginning, and is the beginning, and is with the beginning, is one God.  For the nature of that which is without beginning does not consist in being without beginning or being unbegotten, for the nature of anything lies, not in what it is not but in what it is.  It is the assertion of what is, not the denial of what is not.  And the Beginning is not, because it is a beginning, separated from that which has no beginning.  For its beginning is not its nature, any more than the being without beginning is the nature of the other.  For these are the accompaniments of the nature, not the nature itself.  That again which is with that which has no beginning, and with the beginning, is not anything else than what they are.  Now, the name of that which has no beginning is the Father, and of the Beginning the Son, and of that which is with the Beginning, the Holy Ghost, and the three have one Nature—God.  And the union is the Father from Whom and to Whom the order of Persons runs its course, not so as to be confounded, but so as to be possessed, without distinction of time, of will, or of power.  For these things in our case produce a plurality of individuals, since each of them is separate both from every other quality, and from every other individual possession of the same quality.  But to Those who have a simple nature, and whose essence is the same, the term One belongs in its highest sense.