In the early church subordination was tied to homoiousion of persons. That is the three persons were 'alike' in substance thus being subordinate in essence. The heretics during St. Basil's time refered to the subordinate rankings as subnumeration of rank while Basil refuted this saying it would be accurate to call the ranking of order as a con-numeration.
St. John of Damascus in BK 1 of his Exposition of the faith explains:
Therefore, God is one, perfect, uncircumscribed, maker of the
universe, and its preserver and governor, exceeding and preceding all perfection.
Moreover, it is a natural necessity that duality should originate in unity.
So then this one and only God is not Wordless. And possessing the Word, He will have it not as without a subsistence, nor as having had a beginning, nor as destined to cease to be. For there never was a time when God was not Word: but He ever possesses His own Word, begotten of Himself......But since God is everlasting and perfect, He will have His Word subsistent in Him, and everlasting and living, and possessed of all the attributes of the Begetter. (Chapters 5-6)
....So then in the first sense of the word the three absolutely divine subsistences of the Holy Godhead agree : for they exist as one in
essence and uncreate. But with the second signification it is quite otherwise. For the Father alone is ingenerate , no other subsistence having given Him being. And the Son alone is generate, for He was begotten of the Father's
essence without beginning and without time. And only the
Holy Spirit proceeds from the Father's
essence....... But if we say that the Father is the origin of the Son and greater than the Son, we do not suggest any precedence in time or superiority in nature of the Father over the Son
John 14:28 (for through His agency He made the ages ), or superiority in any other respect save causation... Ch. 8