Arianism is practical paganism, for to make the Son a creature, and at the same time to offer Him worship, is to reintroduce polytheism.  Sabellianism is practical Judaism,—a denial of the Son. cf. ccx. p. 249.  John i. 1, xiv. 9, 7, xvi. 28, and viii. 16 are quoted against both extremes.  There may be a note of time in the admitted impatience of the auditory at hearing of every other subject than the Holy Spirit.  The preacher is constrained to speak upon this topic, and he speaks with the combined caution and completeness which characterize the De Spiritu Sancto.  “Your ears,” he says, “are all eager to hear something concerning the Holy Ghost.  My wish would be, as I have received in all simplicity, as I have assented with guileless agreement, so to deliver the doctrine to you my hearers.  I would if I could avoid being constantly questioned on the same point.  I would have my disciples convinced of one consent.  But you stand round me rather as judges than as learners.  Your desire is rather to test and try me than to acquire anything for yourselves.  I must therefore, as it were, make my defence before the court, again and again giving answer, and again and again saying what I have received.  And you I exhort not to be specially anxious to hear from me what is pleasing to yourselves, but rather what is pleasing to the Lord, what is in harmony with the Scriptures, what is not in opposition to the Fathers.  What, then, I asserted concerning the Son, that we ought to acknowledge His proper Person, this I have also to say concerning the Holy Spirit.  The Spirit is not identical with the Father, because of its being written ‘God is a Spirit.’ John iv. 24.  Nor on the other hand is there one Person of Son and of Spirit, because it is said, ‘If any man have not the spirit of Christ he is none of his.…Christ is in you.’ Rom. viii. 9 and 10.  From this passage some persons have been deceived into the opinion that the Spirit and Christ are identical.  But what do we assert?  That in this passage is declared the intimate relation of nature and not a confusion of persons.  For there exists the Father having His existence perfect and independent, root and fountain of the Son and of the Holy Ghost.  There exists also the Son living in full Godhead, Word and begotten offspring of the Father, independent.  Full too is the Spirit, not part of another, but contemplated whole and perfect in Himself.  The Son is inseparably conjoined with the Father and the Spirit with the Son.  For there is nothing to divide nor to cut asunder the eternal conjunction.  No age intervenes, nor yet can our soul entertain a thought of separation as though the Only-begotten were not ever with the Father, or the Holy Ghost not co-existent with the Son.  Whenever then we conjoin the Trinity, be careful not to imagine the Three as parts of one undivided thing, but receive the idea of the undivided and common essence of three perfect incorporeal [existences].  Wherever is the presence of the Holy Spirit, there is the indwelling of Christ:  wherever Christ is, there the Father is present.  ‘Know ye not that your body is the temple of the Holy Ghost which is in you ?’” 1 Cor. vi. 19.