Tertullian believes that the Son of God is PORTIO TOTIUS whereas the Father is TOTA SUBSTANTIA (Adversus Praxean 9). Later trinitarian formulae, however, saw no need to employ this specific kind of subordinationist nomenclature. On the other hand, Tertullian insisted that the important difference between the Father, Son and Holy Spirit pertained to the STATUS of the Father, not his GRADUS (Adversus Praxean 2). However, despite affirming that the Son is "from the substance of God"(DE SUBSTANTIA DEI), Tertullian nevertheless indicates that the Son lacks certain divine-constituting properties that the Father uniquely instantiates. For an excellent scholarly treatment on the difference between the Latin terms STATUS and GRADUS, see Grillmeier's famed work on Christology. Jean Danielou's history of doctrine in
the Latin church is also highly recommended.