54 Now I ask, whose Godhead is it whereof the fullness dwells in Him? If it be not that of the Father, what other God do you, misleading preacher of one God, thrust upon me as Him Whose Godhead dwells fully in Christ? But if it be that of the Father, inform me how this fullness dwells in Him in bodily fashion. If you hold that the Father abides in the Son in bodily fashion, the Father, while dwelling in the Son, will not exist in Himself. If on the other hand, and this is more true, the Godhead abiding in Him in bodily shape displays within Him the verity of the nature of God from God, inasmuch as God is in Him, abiding neither through condescension nor through will but by birth, true and wholly in bodily fullness according as He is; and inasmuch as, in the whole compass of His being, He was born by His divine birth to be God, and within the Godhead there is no difference or dissimilarity, except that in Christ He dwells in bodily form, and yet whatever dwells in Him bodily is according to the fullness of Godhead; why follow after the doctrines of men?
Why cleave to the teaching of empty falsehoods? Why talk of 'agreement' or 'harmony of will?' or 'a creature?' The fullness of Godhead dwells in Christ bodily.
Source: On the Trinity (New Advent)